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i. Here, the new resistance: R = \(\frac{R}{3}\)

\(\frac{1}{R_{eq}}=\frac{1}{R_1}+\frac{1}{R_2}+\frac{1}{R_3}\)

\(\frac{1}{R_{eq}}=\frac{1}{\frac{R}3}+\frac{1}{\frac{R}3}+\frac{1}{\frac{R}{3}}\)

\(\frac{1}{R_{eq}}=\frac{3}{R}+\frac{3}{R}+\frac{3}{R}\)

\(\frac{1}{R_{eq}}=\frac9R\)

\(\frac{1}{R_{eq}}=\frac9RΩ\)

The resistivity is dependent on the nature of the material. 

Hence, there will be no change in the reisitivity of the wire. 

ii. Now, by Ohm’s Law

V = I x R

I = \(\frac{V}R=\frac{V}{\frac{R}9}=\frac{9V}{R}\)

∴ I = 9 x I

Thus, the current will increase 9 times than the previous current.

Given: 

V = 3V 

R₁ = R₂ = R₃ = R₄ = 10Ω 

Here, R₁ and R₂ are connected in series 

And, R₃ and R₄ are connected in series.

∴ \(\frac{1}{R_{eq}}=\frac{1}{R_1\,+\,R_2}+\frac{1}{R_3\,+\,R_4}\)

\(\frac{1}{R_{eq}}=\frac{1}{R_1\,+\,R_2}+\frac{1}{R_3\,+\,R_4}=\frac{1}{20}+\frac{1}{20}=\frac{2}{20}\)

R_eq = \(\frac{20}{2}\)

Now, by Ohm’s Law

V = I x R

I = \(\frac{V}{R}\) = \(\frac{3}{10}\)

∴ I = 0.3A

Thus, Current drawn by the resistor from the battery is 0.3 A

Correct option  (C) P has maximum current. 

Explanation:

Current at P is maximum because it is connected in series with battery and hence shows total current drawn from battery.

Correct option  (C) While plotting this graph, the temperature remains constant. 

Explanation:

The ratio of potential difference applied to the wire and current passing through it is a constant. Ohm's law is illustrated by this graph. Hence, temperature must be constant while calculating values.

(C) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii) 

Fuse wire is an alloy of tin-lead.

We observe that the bulb in circuit A is not glowing and in circuit B it is glowing. 

We can also see the switch is in OFF mode in circuit diagram A and it is in ON mode in circuit diagram B. Circuit diagram A represents open circuit, where as circuit diagram B represents closed circuit.

(b) Electromagnetic induction

Electric cranes are worked on the principle of magnetic effects of electricity.

The devices which act as magnets when electricity passes through them are called electromagnets.

The production of magnetic force due to the flow of electricity thrombi a wire is called Magnetic effect of electricity.

If a number of cells are connected in series the brightness of the bulb is enhanced.

1. Generally, the filament in an iron box is made up of Niehrome. 

2. The filament in a bulb is made of Tungsten.

If a number of cells are connected in parallel the brightness of the bulb remains same.

The production of heat due to the flow of electricity through a wire is called heating effect of electricity.

A simple electric circuit consisting of a battery, a bulb, a switch, and connecting wires.

Positive terminal of the cell → wire → bulb → wire → switch → wire → negative terminal of the cell.

The diagrams which show the arrangement of electric components in a circuit are called circuit diagrams.

Miniature Circuit Breaker (MCB) is being used in place of electric fuses.

The common sequence of components in electric circuit diagram is as follows :

Positive terminal of  the cell → wire bulb wire → switch → wire → negative terminal of the cell.

A simple electric circuit consisting of a battery, a bulb, a switch and connecting wires.

The diagrams which show the arrangement of electric component’s in a circuit are called circuit diagrams.

Correct Answer is: (c) 1/2

The p.d. between the plates is the same at all the points. As p.d. = intensity x distance, the intensity E is the same in both dielectrics.

Let σ₁ and σ₂ be the charge densities in the upper and lower halves.

∴ E = σ₁/ε₀K = σ₂/ε₀ x 2K 

∴ σ₁/σ₂ = 1/2.

Correct Answer is: (b) move further into the gap

Energy = Q2/2C .Here, Q is constant.

As the slab moves into the gap, C increases and hence energy decreases. A system tends to move towards lower energy.

Correct Answer is: (d) 100 V

Volume = 4/3 πR³ = 1000 x 4/3 πr³ or r = R/10

Q = CV = (4πε₀R) x V = 1000(4πε₀r) 1 

or V = 10³ τ/R = 10³/10 = 100 V

Correct Answer is: (b) equal to T

The additional electrostatic force acts along the string. this dose not have a component in the direction of motion of the bob.

If the amount of work done in bringing a one-coulomb charge from one point to the other is 1 joule then potential difference between two points is said to be 1volt.

False

Insulator like wood and rubber has a very high electrical resistance.

True

With increase in temperature the random motion of the atoms and electrons in a conductor increases and so the resistance decreases.

When a metallic conductor is heated, the atoms in the metal vibrate with greater amplitude and frequency. Due to increase in temperature, the thermal velocities of free electrons also increases. Therefore, the number of collisions between free electrons and atoms increases. This increases the opposition to the movement of electrons and hence the resistance of the conductor.

The resistance of dry-skin human body is about 50,000Ω. When the skin is wet, the resistance gets lowered to about 10,000Ω. If a person with wet hands touches the electrical circuit, high current will flow through the body causing risk to life.

Solution : 

The general name of the substances having infinitely high electrical resistance Insulators. 

Given 

Power (P) = 26W 

Voltage (V) = 220V 

We know that

P = \(\frac{V^2}{R}\)

⇒ R = \(\frac{V^2}{P}\)

⇒ R = \(\frac{220\,\times\,220}{26}\)

⇒ R = \(\frac{48400}{26}\) = 1861.53

Hence the resistance is 1861.53 Ω

Other information is that it will consume energy at the rate of 36 J/s. 

P=V2/R 

R is fixed. 

V becomes double. 

Now, P = (2V)2/R = 4 V2/R 

So, the electric power becomes four times its previous value.

kWh is the short form of kilowatt-hour, which is the commercial unit of electrical energy. 

Electric power has the unit of watt. 

Electric power has the unit of watt.

(i) Electric power

(ii) Electric energy

(i) Electric power (ii) Electric energy