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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.
| 701. |
A body charged positively is considered to be at a `"______"` potential and a body that is charged negatively is considered to be at a `"______"` potential. |
| Answer» Correct Answer - higher, lower | |
| 702. |
A cylindrical conductor of length `l` and uniform area of cross-section `A` has resistance `R`. Another conductor of length `2 l` and resistance `R` of the same material has area of cross-section :A. `A//2`B. `3 A//2`C. `2 A`D. `3 A` |
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Answer» Correct Answer - C As `R = (rho l)/(A)`, when `l` becomes `2 l`, A should be `2 A` so that `R` remains the same. |
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| 703. |
If 100 billion electrons are added to earth, then the potential of the Earth`"_______"` |
| Answer» Correct Answer - remains uncharged | |
| 704. |
When the area of cross-section of a conductor is doubled, its resistance becomes:A. doubleB. halfC. four timesD. one-fourth |
| Answer» Correct Answer - B | |
| 705. |
Match the column the entries given in Column A with the appropriate ones in Column B. |
| Answer» Correct Answer - `A:c B: a C:e D:b E: d` | |
| 706. |
`0.5 C` charge passes through a cross-section of a conductor in `5 s`. Find the current. |
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Answer» Correct Answer - 0.1 A `I = (Q)/(t) = (0.5 C)/(5 s) = 0.1 A`. |
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| 707. |
What are the following symbols mean in an electric circuit. |
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Answer» (a) Rheostat (b) Plug key (closed) |
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| 708. |
The most convenient form of energy is `"_______"` energy. |
| Answer» Correct Answer - electrical | |
| 709. |
Match the column the entries given in Column A with the appropriate ones in Column B. |
| Answer» Correct Answer - `A:c B: a C:e D:b E: d` | |
| 710. |
`"______"` is defined as the rate at which the charges move across any cross section of a conductor. |
| Answer» Correct Answer - strength of eletric current | |
| 711. |
The purpose of `"______"` is to prevent electric shocks. |
| Answer» Correct Answer - earthing | |
| 712. |
The obstruction offered to the passage of electric current by a material is called `"_____"`. |
| Answer» Correct Answer - resistance. | |
| 713. |
Which of the following is the dimensional formula for capacitance `xx ("potential")^(2)`? |
| Answer» Correct Answer - `[M^(-1)L^(-2)T^(4)A^(2)]` | |
| 714. |
The dimensional formula of electric potential is |
| Answer» Correct Answer - `[M^(-1)L^(-2)T^(-2)A^(-1)]` | |
| 715. |
What is the ratio of potential difference and current known as ? |
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Answer» Solution : The ratio of potential difference and current is known as resistance |
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| 716. |
Match the enteries given in Column A with appropriate ones from Column B. lt |
| Answer» Correct Answer - A:b , B:a, C:e, D:g, E:c, F:d, G:j, H:f, I:I, J:h | |
| 717. |
The graph between V and 1 for a conductor is a straight line passing through the origin. Which law is illustrated by such a graph ?What should remain constant in a statement of this law ? |
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Answer» Solution : (a) Ohm’s law (b) Temperature. |
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| 718. |
Name the law which is illustrated by the above V-I graph. |
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Answer» Solution : Ohm’s law |
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| 719. |
The following diagram shows four circuits A, B, C and D. Each circuit has a cell and a torch bulb. Name the circuits in which the bulb will glow ? Give reason to your answer |
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Answer» The bulb will glow in circuit (D). This is because copper is the best conductor of electricity as compared to aluminium. Silk is a non-conductor of electricity. |
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| 720. |
A unit positive charge is moved along the circumfer-ence of a circle of radius, r with a `-5muC` charge at the centre at the centre of the circle. Then, the work done in the process is `"______"`.A. negative work of `100 J`B. positive work of `100 J`C. zeroD. `(Q.1)/(4pi in_(0).r)` |
| Answer» Correct Answer - C | |
| 721. |
A bulb is connected to a cell and the potential differ-ence across the terminals of the bulb is 24 V. If 3 A of current flows through the bulb, then the resitance of its filament is `"_____"omega`.A. 8B. 72C. 24D. 3 |
| Answer» Correct Answer - A | |
| 722. |
Write down the formula which states the relation between potential difference, current and resistance |
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Answer» Solution : Potential difference = Current x Resistane |
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| 723. |
An electric heater draws a current of 10A from a 220V supply. What is the cost of using the heater for 5 hours everyday for 30 days if the cost of 1 unit (1 kWh) is Rs 5.20? |
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Answer» In this problem, first of all we have to calculate the power of the heater by using the given values of current and voltage. This can be done by using the formula: `P = V xx l` Here, Voltage (or p.d), `V = 220V` And, Current, `I = 10A` So, Power, `P = 220 xx 10W` `= 2200W` `= (2200)/(1000) kW` `= 2.2 kW` ....(1) Now, Electric energy consumed, `E = P xx t` Here, Power, `P = 2.2 kW` And, Time, `t = 5h` So, Electric energy consumed in 1 day `= 2.2 xx 5` `= 11 kWh` And, Electric energy consumed in 30 days `= 11 xx 30` `= 330 kWh` (or 330 units) ....(2) Now, Cost of 1 unit of electricity = Rs 5.20 So, Cost of 330 unit of electricity = Rs `5.20 xx 330` = Rs 1716 Before we go further and discuss the heating effect of electric currnet, please answer the following questions: |
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| 724. |
The potential difference between the terminals of an electric iron is 240 V and the current is 5.0 A. What is the resistance of the electric iron ? |
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Answer» V = 240 volt, I = 5amp We know that V=IR 240 = 5 x R R = 240/5 = 48 ohm. |
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| 725. |
An electric room heater draws a current of 2.4 A from the 120 V supply line. What current will this room heater draw when connected to 240 V supply line ? |
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Answer» Solution : In first case, I = 2.4 amp, V = 120 volt V=IR 120 = 2.4 x R R = 120/2.4 = 50 ohm In second case, V = 240 volt, R = 50 ohm V = IR 240 = I x 50 I =4.8 amp. |
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| 726. |
The resistance offered by a wire of unit length and unit cross-sectional area is called resistivity. For a material irrespective of length and area, the resistivity is a constant. It is also called specific resistance of the material. Metals and alloys have low resistivity while insulators have high resistivity. Resistivity of two elements A and B are 1.62 x 10-8 Om and 520 x 10-8 Ωm respectively. Out of these two, name the element that can be used to make : (i) filament of electric bulb. (ii) wires for electrical transmission lines. |
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Answer» (i) Element B It has more resistivity (520 x 10-8 Ωm) (ii) Element A It has less resistivity and hence less heating effect. Dissipation of energy during transmission of Power. |
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| 727. |
Read the directions given below and answer the questions. (a) If both assertion and reason are true and the reason is the correct explanation of the assertion. (b) If both assertion and reason are true, but the reason is not the correct explanation of the assertion. (c) If the assertion is true, but the reason is false. (d) If the assertion is false, but the reason is true.Assertion : Charges flow from higher potential to the lower potential. Reason : Current flows mainly due to flow of electrons |
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Answer» (b) Both assertion and reason are true, but the reason is not the correct explanation of the assertion. |
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| 728. |
Read the directions given below and answer the questions. (a) If both assertion and reason are true and the reason is the correct explanation of the assertion. (b) If both assertion and reason are true, but the reason is not the correct explanation of the assertion. (c) If the assertion is true, but the reason is false. (d) If the assertion is false, but the reason is true. Assertion : Parts of car and bicycle are made iron with chromium coating. Reason : Chromium does not corrode and resist scratches |
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Answer» (a) Both assertion and reason are true and the reason is the correct explanation of the assertion. |
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| 729. |
How does the resistance of a wire vary with its : (a) area of cross-section ? (b) diameter ? |
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Answer» Solution : (a) By increasing the area of cross section, the resistance will decrease. (b) By increasing the diameter, the resistance will decrease. |
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| 730. |
Match the following:1. Insulator(a) Coulomb2. Conductor(b) Electric circuit3. Closed path(c) Copper4. Electric charge(d) Rubber |
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Answer» 1. b 2. c 3. d 4. a |
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| 731. |
Match the following:1. Bulb(a) Conductor2. Electroplating(b) Insulator3. Pure water(c) Heating effect of current4. Salt solution(d) Chemical effect of current |
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Answer» 1. c 2. d 3. b 4. a |
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| 732. |
Three identical bulbs are connected as shown in fig-ure. Choose the correct statement. A. All bulbs are in a series combination.B. If bulb R is removed, bulb P and Q will still glow.C. The total e.m.f in th circuitis 40 V.D. The given circuit is an open circuit. |
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Answer» Correct Answer - A (a) From the circuit diagram it is clear that all the single bulbs are in a series combination: (b) If bulb R is removed from the given series com-bination, the remaining bulbs will not glow, because it creates an open circuit. (c ) The cells in the given circuit are in series with each other, and hence, the total e.m.f. of this combination = `(20+40) V = 60 V`. (d) The switch S in the circuit is switched off, and hence, it is an open circuit. |
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| 733. |
True or False – if false give the correct statement1. Materials which do not allow electric charges to pass through them easily are called insulator.2. Silk cloth has excess of electrons, so it becomes positively charged.3. Electric charge is measured in coulomb.4. Protons carry negative charge and the electrons carry positive charge.5. The gold – leaf electroscope was developed by Abraham Bennet. |
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Answer» 1. True 2. False Correct statement: Silk cloth has excess of electrons, so it becomes negatively charged. 3. True 4. False. Correct statement: Protons carry positive charge and the electrons carry negative charge. 5. True |
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| 734. |
Mention one reason why tungsten is exclusively used for making filaments of electric lamps. |
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Answer» Tungsten has a high resistivity and a high melting point. So, most of the power consumed by this is dissipated in the form of heat. |
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| 735. |
Why are filaments of incandescent lamps made of thin tungsten wire ? |
| Answer» Tungsten has low resistivity and as such only a thin wire filament will high resistance necessary to produce large amount of heat to light the bulb brilliantly. Further, tungsten has very high melting point `(3300 K)` and as such the filament will not burn at the high temperature `(2400 K)` at which it becomes incandescent. | |
| 736. |
Materials that do not allow electric charges to flow through then are called `"______"`. |
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Answer» Correct Answer - insulators Materials that do not allow electric changes to flow through thems are called insulators. |
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| 737. |
Glass does not allow _______ to flow through it. |
| Answer» Correct Answer - Electric charge | |
| 738. |
Why is nichrome used as a heating element ? |
| Answer» Correct Answer - High resistivity | |
| 739. |
The types of cells in which it is possible to restore the chemicals are called ___________ . |
| Answer» Correct Answer - Secondary cells | |
| 740. |
Name the common chemicals present in the dry cell. |
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Answer» 1. Carbon powder 2. Ammonium chloride. |
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| 741. |
Which parts of the battery function as an anode and a cathode? |
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Answer» 1. The container which is made of zinc metal works as the cathode (negative terminal). 2. A carbon rod with a metal cap works as an anode (positive terminal). |
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| 742. |
Identify the series combination in the following circuit. |
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Answer» Figure I and IV have series combinations only. Resistance are placed between terminal A and B only. |
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| 743. |
Which of these represent relation between voltage (V) and current (I) ? |
| Answer» Figure B. It verifies Ohm's Law. | |
| 744. |
Which of the following is a false statement about Leclanche cell ?A. Electrolyte is a liquid.B. Zinc rod and carbon rod acts as negative and positive electrodes.C. It can be easily portable form place from place to place.D. Dry cell is a modified form of Leclanche cell. |
| Answer» Correct Answer - C | |
| 745. |
Which of the following is not an electrical appliance ?A. Washing machineB. TVC. Fire extinguisherD. Water cooler |
| Answer» Correct Answer - C | |
| 746. |
Where do we used dry cells? |
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Answer» In our daily life we use dry cells in torch lights, wall clocks, radios etc. |
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| 747. |
Which of the following is not a depolarizer ?A. Potassium dichromateB. Copper sulphateC. Mercury oxideD. Manganese dioxide. |
| Answer» Correct Answer - C | |
| 748. |
A current carrying metallic comb is placed close to small iron filings, then theA. iron filings will fly away from the comb, when switch is turned off.B. iron filing will fly away from the comb, when switch is turned off.C. iron filings align in the direction of the magnetic field produced around the metallic comb.D. iron filing will be attracted by the comb. |
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Answer» Correct Answer - B As the switch is turned on, the current flows through the circuit and magnetic field will be produced around it. All iron filings will align in the direction of a magnetic field. But the metallic comb will not behave, like an electro magnet, and hence the iron filings will neither be attracted nor repelled. |
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| 749. |
A current carrying metallic comb is placed close to small iron filings, then theA. iron filings will fly away from the comb, when switch is turned off.B. iron filings align in the direction of the magentic field produced around the metallic comb.C. iron filings wil be attracted by the comb.D. Both (a) and (b) |
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Answer» Correct Answer - B As the switch is turned ON, he current flows through the circuit and magnetic field will be produced around it. All iron filings wil align in the direction fo a magnetic field. But the metallic comb will not behave, like an electro magnet, and hence, the iron filings will neither be attracted nor repelled. |
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| 750. |
Prahar took two identical heating elements and con-nected them to a battery in two different ways as shown in the figure. When he switched ON the switch, is the heat developed in each element the same or different in both the cases ? |
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Answer» Heat generated in two ideantical heating elements depends on the current that flows through them. More the current that passes through an element, more is the heat generated. In. Fig (A) heating elements are connected in series and in Fig(B) heating elements are connected in par-allel. the current that flows through the heating ele-ments when they are connected in series is less than the current that flow through them when they are connected in parallel. As such more heat is generated when they are connected as shown in the Fig. (B). |
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