Current Electricity

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

Find the equivalent resistance between two ends of the following circuit [figure]

1. r
2. r6
3. r3
4. r9

A wire of resistance R is bent into an equilateral triangle and an identical wire is bent into a square. The ratio of resistance between the two end points of an edge of the triangle to that of the square is

1. 8/9
2. 9/8
3. 32/27
4. 27/32

The value of current I in the electrical circuit as given below, when potential at A is equal to the potential at B, will be A. [figure]

A wire of resistance 9 is bent to form an equilateral triangle. Then the equivalent resistance across any two vertices will be ohm.

Refer to the circuit diagram given in the figure. which of the following observations are correct? [figure] Choose the correct answer from the options given below:

1. B, C and E Only
2. A, C and D Only
3. A, B and C Only
4. A, B and D Only

Identify the valid statements relevant to the given circuit at the instant when the key is closed. [figure] Choose the correct answer from the options given below:

1. A, C Only
2. C, D Only
3. A, B, D Only
4. B, C, D Only

At steady state the charge on the capacitor, as shown in the circuit below, is . [figure]

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below.

1. Statement-I is false but Statement-II is true
2. Statement-I is true but Statement-II is false
3. Both Statement-I and Statement-II are false
4. Both Statement-I and Statement-II are true

Which of the following resistivity ( ) v/s temperature ( T ) curves is most suitable to be used in wire bound standard resistors?

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

Sliding contact of a potentiometer is in the middle of the potentiometer wire having resistance Rp=1 as shown in the figure. An external resistance of Re=2 is connected via the sliding contact. The electric current in the circuit is : [figure]

1. 1.35 A
2. 0.9 A
3. 1.0 A
4. 0.3 A

The net current flowing in the given circuit is A. [figure]

The equivalent resistance between A and B is : [figure]

1. 18
2. 27
3. 19
4. 25

The current flowing through the 1 resistor is n10 A. The value of n is . [figure]

The effective resistance between A and B, if resistance of each resistor is R, will be : [figure]

1. 8R3
2. 4R3
3. 23R
4. 5R3

To determine the resistance (R) of a wire, a circuit is designed below. The V-I characteristic curve for this circuit is plotted for the voltmeter and the ammeter readings as shown in figure. The value of R is . [figure]

At room temperature (27 ), the resistance of a heating element is 50 . The temperature coefficient of the material is 2.4 10-4 C-1. The temperature of the element, when its resistance is 62 , is .

In the given circuit, the terminal potential difference of the cell is : [figure]

1. 3 V
2. 4 V
3. 2 V
4. 1.5 V

Resistance of a wire at 0 , 100 and t is found to be 10 , 10.2 and 10.95 respectively. The temperature t in Kelvin scale is .

Water boils in an electric kettle in 20 minutes after being switched on. Using the same main supply, the length of the heating element should be to times of its initial length if the water is to be boiled in 15 minutes.

1. increased, 34
2. increased, 43
3. decreased, 34
4. decreased, 43

A heater is designed to operate with a power of 1000 W in a 100 V line. It is connected in combination with a resistance of 10 and a resistance R, to a 100 V mains as shown in figure. For the heater to operate at 62.5 W, the value of R should be . [figure]

The value of unknown resistance (x) for which the potential difference between B and D will be zero in the arrangement shown, is : [figure]

1. 3
2. 42
3. 6
4. 9

A wire of resistance R and radius r is stretched till its radius became r/2. If new resistance of the stretched wire is x R, then value of x is .

The number of electrons flowing per second in the filament of a 110 W bulb operating at 220 V is : (Given e = 1.6 10-19 C)

1. 1.25 1019
2. 31.25 1017
3. 6.25 1018
4. 6.25 1017

In the given figure R1 = 10 , R2 = 8 , R3 = 4 and R4 = 8 . Battery is ideal with emf 12 V. Equivalent resistance of the circuit and current supplied by battery are respectively : [figure]

1. 12 and 11.4 A
2. 10.5 and 1.14 A
3. 10.5 and 1 A
4. 12 and 1 A

The electric field between the two parallel plates of a capacitor of 1.5 capacitance drops to one third of its initial value in 6.6 when the plates are connected by a thin wire. The resistance of this wire is . (Given, e 3 = 1.1)