Current Electricity · Question 25

A battery with EMF E and internal resistance r is connected across a resistance R. The power consumption in R will be maximum when:

1. R = 2r
2. R = 2r
3. R = r2
4. R = r

A wire of resistance R is bent into a triangular pyramid as shown in figure with each segment having same length. The resistance between points A and B is R/n. The value of n is : [figure]

1. 16
2. 10
3. 12
4. 14

Current passing through a wire as function of time is given as I(t) = 0.02t + 0.01 A. The charge that will flow through the wire from t = 1 s to t = 2 s is

1. 0.02 C
2. 0.07 C
3. 0.06 C
4. 0.04 C

There are 'n' number of identical electric bulbs, each is designed to draw a power p independently from the mains supply. They are now joined in series across the mains supply. The total power drawn by the combination is :

1. np
2. p
3. pn2
4. pn

From the combination of resistors with resistance values R1 = R2 = R3 = 5 and R4 = 10 , which of the following combination is the best circuit to get an equivalent resistance of 6 ?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

A wire of length 25 m and cross-sectional area 5 mm2 having resistivity of 2 10-6 m is bent into a complete circle. The resistance between diametrically opposite points will be

1. 100
2. 2.5
3. 12.5
4. 50

In the figure shown below, a resistance of 150.4 is connected in series to an ammeter A of resistance 240 . A shunt resistance of 10 is connected in parallel with the ammeter. The reading of the ammeter is mA. [figure]

A motor operating on 100 V draws a current of 1 A. If the efficiency of the motor is 91.6\%, then the loss of power in units of cal/s is

1. 6.2
2. 2
3. 8.4
4. 4

Two cells of emfs 1 V and 2 V and internal resistances 2 and 1 , respectively, are connected in series with an external resistance of 6 . The total current in the circuit is I1. Now the same two cells in parallel configuration are connected to same external resistance. In this case, the total current drawn is I2. The value of ( I1I2 ) is x3. The value of x is .

The battery of a mobile phone is rated as 4.2 V, 5800 mAh. How much energy is stored in it when fully charged?

1. 87.7 kJ
2. 43.8 kJ
3. 48.7 kJ
4. 24.4 kJ