A 4 μF capacitor and a resistance of 2.5 MΩ are in series with a 12 V battery. The time after which the potential difference across the capacitor is 3 times the potential difference across the resistor is: [Given ln(2)= 0.693] 

1. 13.86 s

2. 6.93 s

3. 7 s

4. 14 s

Three identical capacitors are given a charge Q each and they are then allowed to discharge through resistance R₁, R₂ and R₃. Their charges, as a function of time shown in the graph below. The smallest of the three resistance is

(1) R₃

(2) R₂

(3) R₁

(4) Cannot be predicted

In the given figure each plate of capacitance C has partial value of charge equal to:

1. CE

2. $\frac{CE{R}_1}{R_2-r}$

3. $\frac{CE{R}_2}{R_2+r}$

4. $\frac{CE{R}_1}{R_1-r}$

In the circuit here, the steady state voltage across capacitor C is a fraction of the battery e.m.f. The fraction is decided by 

(1) R₁ only

(2) R₁ and R₂ only

(3) R₁ and R₃ only

(4) R₁, R₂ and R₃

A capacitor of capacitance 5 μF is connected as shown in the figure. The internal resistance of the cell is 0.5 Ω. The amount of charge on the capacitor plate is?

(1) 0 μC

(2) 5 μC

(3) 10 μC

(4) 25 μC

In the circuit shown, the current through the 4 $\Omega$ resistor is 1 A when the points P and M are connected to a DC voltage source. The potential difference  between the points M and N is 

1. 1.5 V 

2. 1.0 V

3. 0.5 V 

4. 3.2 V

A cell can be balanced against 110cm and 100 cm of potentiometer wire, respectively with and without being short-circuited through a resistance of $10 \Omega$. Its internal resistance is 

(1) 1.0 $\Omega$

(2) 0.5 $\Omega$

(3) 2.0 $\Omega$

(4) zero 

An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from temperature ${20}^{°}$C? The temperature of boiling water is ${100}^{°}$C

(a) 6.3 min

(b) 8.4 min

(c) 12.6 min

(d) 4.2 min

A wire of a certain material is streched slowly by ten per cent. Its new resistance and specific resistance become respectively 

(1) 1.2 times, 1.1 times

(2) 1.21 times,same 

(3) both remain the same

(4) 1.1 times, 1.1 times

A current of 3A flows through the 2$\Omega$ resistor shown in the circuit. The power dissipated in the $5\Omega$ resistor is

(a) 4 W                                              (b) 2 W

(c) 1 W                                              (d) 5 W