﻿ The resistance of an incandescent lamp is | Current Electricity

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# 211.The resistance of an incandescent lamp issmaller when switched on greater when switched off the same whether it is switch off or switch on greater when switched on

D.

greater when switched on

t = average time interval between two successive collision or electrons. When switched on, temperature of filament increases, there by K.E. of $\overline{\mathrm{e}}$ increases which increases the velocity of electron. Hence time interval (t) between two collision decreases, hence R increases.

212.

An ammeter and a voltmeter are joined in series to a cell. Their readings are A and V respectively. If a resistance is now joined in parallel with the voltmeter, then

• A will decrease, V will increase

• A will increase, V will decrease

• both A and V will increase

• both A and V will decrease

213.

If each of the resistance of the network shown in figure is R, the equivalent resistance between A and B is

• 3R

• 5R

• $\frac{\mathrm{R}}{2}$

• R

214.

A cell supplies a current of 0.9 A through a 2 Ω resistor and a current of 0.3 A through a 7 Ω resistor. The internal resistance of the cell is

• 1.2 Ω

• 2.0 Ω

• 0.5 Ω

• 1.0 Ω

215.

A and B are two conductors carrying a current I in the same direction. x and y are two electron beams moving in the same direction. Then there will be

• attraction between A and B, repulsion between x and y

• repulsion between A and B, attraction between x and y

• attraction between A and B and x and y

• repulsion between A and B and x and y

216.

The current-voltage graph for a given metallic conductor at two different temperature T1 and T2 are as shown in the figure. Then

• T1 < T2

• nothing can be said about T1 and T2

• T1 = T2

• T1 > T2

217.

The current-voltage graph for a given metallic conductor at two different temperature T1 and T2 are as shown in the figure. Then

• T1 < T2

• nothing can be said about T1 and T2

• T1 = T2

• T1 > T2