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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1001. |
What are the characteristic properties of fuse wire? |
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Answer» Characteristic properties of a fuse wire: (i) It is made up of an alloy of lead and tin. (ii) It has high resistivity and low melting point. |
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| 1002. |
A substance has nearly zero resistance at a temperature of 1K. What is such a substance called? |
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Answer» Super conductor. |
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| 1003. |
An electric kettle connected to the 230 V mains supply draws a current of 10 A. Calculate : (a) the power of the kettle. (b) the energy transferred in 1 minute. |
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Answer» Given V = 230v, I = 10amp (a) P = IV P = 230 x 10 p = 2300 w = 2300 J/s (b) Energy consumed in minute = P x T = 2300 x 60 = 138000j |
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| 1004. |
What is the maximum power in kilowatts of the appliance that can be connected safely to a 13 A ; 230 V mains socket ? |
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Answer» I = 13 amp, V = 230v Power = VI = 230 x 13 = 2990W P =2.99kW |
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| 1005. |
Electricians wear rubbers gloves because it is ____________ (a) soft (b) an insulator (c) conductor (d) water proof |
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Answer» Correct answer is (b) an insulator |
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| 1006. |
Why do electricians wear rubber hand gloves while working with electricity ? |
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Answer» Electricians wear rubber hand gloves while working with electricity because rubber is an insulator and protects them from electric shocks. |
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| 1007. |
Why do electricians wear rubber hand gloves while working with electricity ? |
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Answer» Solution : Electricians wear rubber hand gloves while working with electricity because rubber is an insulator and protects them from electric shocks. |
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| 1008. |
___ are materials that do not allow electric current to pass through them (a) Insulator (b) Conductor (c) Switch (d) Battery |
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Answer» Insulator are materials that do not allow electric current to pass through them. |
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| 1009. |
Materials which allow current to pass through them easily are called? (a) Insulator (b) Conductor (c) Switch (d) Battery |
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Answer» Correct answer is (d) Battery |
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| 1010. |
Would the bulb glow in the circuit shown in Fig. |
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Answer» No, the bulb will not glow because the wires from both terminal of the battery are connected to the one terminal of the bulb. In order to make the bulb glow, wires should be connected to the terminals of the bulb |
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| 1011. |
What is the purpose of using an electric switch? Name some electrical gadgets that have switches built into them. |
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Answer» Electric switch is used to make electric circuit open or closed for a particular appliance and hence with the help of a switch we can use an appliance according to our desire. The electrical gadgets that have built in switches are Electric Iron, AC, Microwave. |
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| 1012. |
What is the purpose of using an electric switch. Name some electrical gadgets that have switches built into them. |
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Answer» An electric switch helps in making as well as breaking the circuit without removing the connection When switch is ON, the current will flow in the circuit, thus, it also saves electricity and make the use of appliances easier. Some electric gadgets are: Television, iron box, Washing machine, Refrigerator etc. |
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| 1013. |
The resistors R1, R2, R3 and R4 in the figure given below are all equal in value. What would you expect the voltmeters A, B and C to read assuming that the connecting wires in the circuit have negligible resistance ? |
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Answer» Req = R + R + R + R = 4R ohm Total current in the circuit, I = V/R = 12/4R = 3/R Reading of voltmeter A = Voltage across R1 = I x R1 = 3/R x R = 3V Reading of voltmeter B = Voltage across R2 = I x R2 = 3/R x R = 3V Reading of voltmeter C = Voltage across the series combination of R3 and R4 = Ix(R3 + R4) = 3/R x 2R = 6V |
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| 1014. |
Explain why, the current that makes the heater element very hot, only slightly warms the connecting wires leading to the heater |
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Answer» The connecting wires of the heater get only slightly warm because they have extremely low resistance due to which negligible heat is produced in them by passing current. |
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| 1015. |
Which of the following property can levitate a magnetic object? A) Heat effect of electricity B) light effect of electricity C) Chemical effect of electricity D) Magnetic effect erf etedtricity |
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Answer» The correct option is D) Magnetic effect erf etedtricity. |
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| 1016. |
Give the examples where the principle of heating effect of electricity is used ? |
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Answer» Electric stove, electric room heater, electric iron box, electric kettle etc. are working on the principle of heating effect of electricity. |
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| 1017. |
Give the examples of working principle of magnetic effect of electricity? |
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Answer» Electric fan, electric bell, electric motor are working on the principle of magnetic effect of electricity. |
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| 1018. |
From where power comes to our houses ? |
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Answer» Electricity supplied to our houses comes from power stations and substations. |
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| 1019. |
The bulbs in houses are connected inA. parallel combinationB. series combinationC. series and parallel.D. neither in series nor in parallel. |
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Answer» Correct Answer - A Generally the bulbs or electrical appliances of house hold are connected in parallel combination. It is to avoid the interruption of power for the glow (work-ing) of bulb (appliance) when any of the electrical appliance (bulb) gets damaged. |
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| 1020. |
A current of `0.2 A` flows through a conductor of resistance `4.5 Omega`. Calculate the potential difference at the ends of the conductor. |
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Answer» Correct Answer - 0.9 V `V = IR = (0.2 A)(4.5 Omega) = 0.9 V`. |
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| 1021. |
An incandescent lamp of resistance `80 Omega` draws a current of `0.75 A`. Find the line voltage. |
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Answer» Correct Answer - 60 V `V = IR = (0.75 A)(80 Omega) = 60 V`. |
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| 1022. |
(a) If a number of bulbs of different wattages are joined in parallel, which bulb will glow with maximum brigthness ? (b) Which bulb will glow with maximum brightness in case bulbs of different wattages are joined in series ? |
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Answer» (a) The bulb with highest wattage (lowest resistance) glows with maximum brightness as `P = V^2//R`. (b) The bulb with lowest wattage (highest resistance) glows with maximum brightness as `P = I^2 R`. |
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| 1023. |
In an electrical circuit, two resistors of `2 Omega and 4 Omega` respectively are connected in series to a `6 V` battery. The heat dissipated by the `4 Omega` resistor in `5 s` will be :A. 5 JB. 10 JC. 20 JD. 30 J |
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Answer» Correct Answer - C Given, resistors, `R_(1) = 2 Omega " and " R_(2) = 4 Omega` Voltage, `V = 6 V_(1)` Time, t = 5s Resistance, `R = 4 Omega` Heat dissipated, H = ? Resistor, `R_(s) = R_(1) + R_(2) = 2 + 4 = 6 Omega` Current, `I = (V)/(R) = (6)/(6) = 1A`. Heat dissipated `H = I^(2)Rt = 1 xx 4 xx 5 = 20 J` |
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| 1024. |
Which combination of resistors is used to decrease current in a circuit ? |
| Answer» Series combination of resistors. | |
| 1025. |
An electric bulb is connected to a `220 V` generator. The current is `0.50 A`. What is the power of the bulb ? |
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Answer» P=VI `=220Vxx0.50A` `=110j//s` =110 W. |
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| 1026. |
(a) Why does resistance increase in a series combination of resistors ? (b) Why does resistance decrease in a parallel combination of resistors ? |
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Answer» (a) Connecting a number of resistors in series is equivalent to increasing the effective length (l) of the conductor. Recall `R prop l`. (b) Connecting a number of resistors in parallel is equivalent to increasing the effective cross-sectional area (A) of the conductor Recall `R prop 1//A`. |
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| 1027. |
What happens it the pd across a resistance is doubled ? |
| Answer» The current through the resistance is doubled as `I = V//R`. | |
| 1028. |
Which of the following represents voltage ?A. `("Work done")/("Current" xx "Time")`B. Work done `xx` ChargeC. `("Work done" xx "Time")/("Current")`D. Work done `xx` Charge `xx` Time |
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Answer» Correct Answer - A As `W = VI t, V = (W)/(I xx t)`, i.e.,Voltage `= ("Work done")/("current" xx "Time")`. |
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| 1029. |
(a) How does the current divide itself in a parallel combination of resistors ? (b) How does the pd divide itself in a series combination of resistors ? |
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Answer» (a) The current divides in the inverse ratio of the resistances. (b) The pd across any one of the resistors is directly proportional to its resistance. |
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| 1030. |
What is the minimum resistance which can be made using five resistors each of `(1//5) Omega` ?A. `1//5 Omega`B. `1//25 Omega`C. `1//10 Omega`D. `25 Omega` |
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Answer» Correct Answer - B The minimum resistance is obtained when resistors are connected in parallel combination. Thus, equivalent resistance, `R_(P) = (R)/(n) = (1//5)/(5) = (1)/(25) Omega, R_(p)` = equivalent resistance for parallel combination. |
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| 1031. |
A wire having a resistance of `18 Omega` is cut into three equal parts. What is the equivalent resistance if these three parts are joined in parallel ? |
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Answer» Resistance of each part, `r = 18 Omega//3 = 6 Omega` Since these three parts are joined in parallel, the equivalent resistance, `R = r//3 = 6 Omega//3 = 2 Omega`. |
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| 1032. |
Five resistors, each `3 Omega`, are connected as shown in (fig. 3.23). Calculate the resistance between the points (a) A and b between the point `C and D`. . |
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Answer» Correct Answer - (a) `2 Omega` (b) `8 Omega`. (i) In (Fig. 3.23), resistance in the arm `AEB`, i.e., `R_1 = 3 Omega + 3 Omega = 6 Omega` As `R_1(= 6 Omega) and 3 Omega` (in arm AB) are in parallel, effective resistance between the points `A and B`, i.e., `R = (6 xx 3)/(6 + 3) Omega = 2 Omega` (ii) Since the effective resistance between points `A and B(i.e., 2 Omega)` and in the arm `AC(= 3 Omega)` and arm `BD(= 3 Omega)` are in series, effective resistance between the points `C and D = 2 + 3 + 3 = 8 Omega`. |
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| 1033. |
What is the minimum resistance which can be made using five resistors each of `(1//5) Omega` ?A. `(1//5) Omega`B. `(1//25) Omega`C. `(1//10) Omega`D. `25 Omega` |
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Answer» Correct Answer - B Minimum resistance is obtained in parallel combination. Thus, `R_p = ((1//5 Omega))/(5) = (1//25) Omega`. |
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| 1034. |
The device used to measure electric current in a cir-cuit is called `"_____"`A. speedometerB. ammeterC. voltmeterD. kilowat hour meter |
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Answer» Correct Answer - B The device used to measure electric currentin a cir-cuit is "Ammeter". |
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| 1035. |
What is the maximum resistance which can be made using five resistors each of `(1//5) Omega` ?A. `1//5 Omega`B. `10 Omega`C. `5 Omega`D. `1 Omega` |
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Answer» Correct Answer - D The maximum resistance is obtained when resistors are connected in series combination. Thus equivalent resistance `R_(s) = n xx R = 5 xx (1)/(5) = 1 Omega, R_(s)` = equivalent resistance for parallel combination. |
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| 1036. |
What is the ratio of equivalent resistance of series combination of `n` equal resistance to the equivalent resistance in parallel combination of these `n` resistances ? |
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Answer» Equivalent resistance of series combination of `n` equal resistances (each resistance equal to `r`), i.e., `R_s = nr` Equivalent resistance of parallel combination of `n` equal resistance (each resistance equal to `r`), i.e., `R_p = (r )/(n)` Thus, `(R_s)/(R_p) = (n r)/(r//n) = n^2`. |
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| 1037. |
(a) When is the pd for all the resistors in a circuit the same and is equal to applied pd ? (b) When is the current through all the resistors in a circuit the same and is equal to the total current in the circuit ? |
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Answer» (a) When the resistors are connected in parallel. (b) When the resistors are connected in series. |
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| 1038. |
How does the resistivity of an alloy such as constantace depends on temperature. |
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Answer» The resistivity of an alloy almost remains unaffected with change in tempeature. |
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| 1039. |
Fill in the blanks.a) Longer line in the symbol for a cell represents its ………… terminal. b) Smaller line in the symbol for a cell represents its ………… terminal. c) The combination of two or more cells is called a ………… . d) Safety device used in electric circuit is ………… . e) The device used to close or open an electric circuit is ………… . |
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Answer» a) positive b) negative c) battery d) fuse e) switch |
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| 1040. |
Which of the following represents voltage?(a) \(\frac{Workdone}{Current \times Time}\)(b) Workdone x Charge(c) \(\frac{Workdone\times Time}{Current}\)(d) Work done x Charge x Time |
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Answer» The answer is (a) \(\frac{Workdone}{Charge\times Time}\) |
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| 1041. |
The proper representation of series combination of cells obtaining maximum potential is A. (i)B. (ii)C. (iii)D. (iv) |
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Answer» Correct Answer - A The proper representation of series combination of cells is that the negative terminal of the first cell is connected to the positive terminal of the second cell and the negative terminal of second cell is connected to the positive terminal of the third cell and so on. |
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| 1042. |
(a) Whose resistivity increases more with temperature : of an alloy or of its constituent metals ? (b) Name a material whose resistivity becomes zero at a particular temperature ? |
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Answer» (a) Constituent metals (b) Mercury `(at 4.2 K)`. |
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| 1043. |
The proper representation of the series combination of cells obtaining maximum potential is(a) (i) (b) (ii) (c) (iii) (d) (iv) |
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Answer» The answer is (a) (i) Here positive terminal of next cell is adjacent to negative terminal of previous cell. |
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| 1044. |
Identify the circuit, (Fig. 3.39) in which the electrical components have been properly connected. A. (i)B. (ii)C. (iii)D. (iv) |
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Answer» Correct Answer - B While identifying the circuit, the following conditions must be satisfied. (a) An ammeter is always connected in series. (b) The voltmeter should be connected in parallel (c0 The positive terminals of V and A should be joined to positive terminal of the cell and their negative terminals should be joined to the negative terminal of the cell. Thus, the above conditions are in case (ii). |
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| 1045. |
What is the minimum resistance which can be made using five resistors each of 1/5 Ω? (a) 1/5 Ω (b) 1/25 Ω (c) 1/10 Ω (d) 25 Ω |
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Answer» The answer is (b) 1/25 Ω Minimum resistance is obtained when resistors are connected parallel 1 /R = 5 + 5 + 5 +5 +5 = 25 Ω R = 1/25 You know, equivalent resistance decreases when resistors are joined in parallel.e.g., 1/Req = 1/R₁ + 1/R₂ + 1/R₃ + 1/R₄ + ....... + 1/Rn . While equivalent resistance increases when resistors are joined in series e.g., Req = R₁ + R₂ + R₃ + .... + Rn. it Means, we can get minimum resistance when all the given resistors will join in parallel. And we can get maximum resistance when all the resistors will join in series . ∴ for finding minimum resistance , we have to join all resistors in parallel. So , 1/Req = 1/(1/5) + 1/(1/5) + 1/(1/5) + 1/(1/5) + 1/(1/5) 1/Req = 5 + 5 + 5 + 5 + 5 = 25 Req = 1/25 Ω Hence , minimum resistance = 1/25 Ω |
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| 1046. |
An electric bulb is marked `250 W - 200 V`. What information does it convey ? How many Joules of energy is consumed by this bulb in one hour ? How long will it take for the bulb to consume `1 kWh` ? |
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Answer» Correct Answer - 900000 J, 4 h A `250 W - 200 V` bulb consumes an electric power of `250 W` when working on `200 V` and the resistance of such a bulb is `(200 V)^2//250 W = 160 Omega (as P = V^2//R or R = V^2//P)`. `W = Pt = (250 W)(60 xx 60 s) = 900000 J` As `W = Pt, t = (W)/(P) = (1 kWh)/(250 W) = (1000 Wh)/(250 W) = 4 h`. |
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| 1047. |
What is the potential difference between the terminals of a battery if 250 joules of work is required to transfer 20 coulombs of charge from one terminal of battery to the other ? |
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Answer» Solution : Given: Work done = 250J, Charge moved = 20C. we know that,Potential difference = Work done/Charge moved =250/20=12.5 |
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| 1048. |
Three different circuits (I, II and III) are constructed using identical batteries and resistors of R and 2R ohm. What can be said about current I in arm AB of each circuit.A. II > III > IIIIB. II < III < IIIIC. III < II < IIII D. II = III = IIII |
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Answer» The equivalent in all the three circuits comes out to be the same so II = III = IIII. The reason being, the two end resistors of R and R ohms add upto 2R and the subsequently the two resistors of 2R in parallel are equivalent to a single resistor of R ohms and then the process repeats until the arm AB is reached , so, finally the equivalent resistance of all the circuits is same. |
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| 1049. |
A current of `1 A` is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in `16` seconds would be roughly :A. `10^20`B. `10^10`C. `10^18`D. `10^23` |
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Answer» Correct Answer - A As `Q = I t = (1 A)(16 s) = 16 C, n = (Q)/( e) = (16 C)/(1.6 xx 10^-19 C) = 10^20`. |
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| 1050. |
A current of `1 A` is drawn by a filament of an electric bulb. Number of electrons passing through a cross-section of the filament in `16` seconds would be roughly :A. `10^(20)`B. `10^(16)`C. `10^(18)`D. `10^(23)` |
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Answer» Correct Answer - A Given, current, I = 1 A Time, t = 16 s Number of electrons n = ? We know that, Current, `I = (Q)/(t) = ("ne")/(t)` `" "[because e = "Charge of an electron" = 1.6 xx 10^(-19)C and Q = "ne"]` `rArr` `" "n = (It)/(e) = (1 xx 16)/(1.6 xx 10^(-19)) = 10^(20)` |
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