Current Electricity

A potential divider circuit is shown in figure. The output voltage V0 is : [figure]

1. 2 mV
2. 4 V
3. 0.5 V
4. 12 mV

An electric toaster has resistance of 60 at room temperature (27 ). The toaster is connected to a 220 V supply. If the current flowing through it reaches 2.75 A, the temperature attained by toaster is around : ( if =2 10-4/ )

1. 1235
2. 1667
3. 694
4. 1694

Two cells are connected in opposition as shown. Cell E1 is of 8 V emf and 2 internal resistance; the cell E2 is of 2 V emf and 4 internal resistance. The terminal potential difference of cell E2 is V. [figure]

When a potential difference V is applied across a wire of resistance R, it dissipates energy at a rate W. If the wire is cut into two halves and these halves are connected mutually parallel across the same supply, the energy dissipation rate will become:

1. 1/2W
2. 4W
3. 1/4W
4. 2W

Two resistances of 100 and 200 are connected in series with a battery of 4 V and negligible internal resistance. A voltmeter is used to measure voltage across 100 resistance, which gives reading as 1 V. The resistance of voltmeter must be .

The electric current through a wire varies with time as I=I0+ t, where I0=20 A and =3 A/s. The amount of electric charge crossed through a section of the wire in 20 s is :

1. 80 C
2. 800 C
3. 1000 C
4. 1600 C

In the given circuit, the current in resistance R3 is : [figure]

1. 2 A
2. 1.5 A
3. 1 A
4. 2.5 A

In the given circuit, the current flowing through the resistance 20 is 0.3 A, while the ammeter reads 0.9 A. The value of R1 is . [figure]

In the given figure, the charge stored in 6 capacitor, when points A and B are joined by a connecting wire is . [figure]

A wire of length 10 cm and radius 7 10-4 m is connected across the right gap of a meter bridge. When a resistance of 4.5 is connected on the left gap by using a resistance box, the balance length is found to be at 60 cm from the left end. If the resistivity of the wire is R 10-7 , then value of R is :

1. 63
2. 70
3. 66
4. 35