emf, internal resistance and combinations of cells — NEET & JEE Questions

Question 1 · difficulty L1 · recall

The emf of a cell is the work done by the cell per unit

• A. charge
• B. current
• C. resistance
• D. power

Question 2 · difficulty L2 · understanding

When an external resistance of $5 \Omega$ is connected across terminals of a cell, a current of 0.25 A flows through it. When the $5 \Omega$ resistor is replaced by a $2 \Omega$ resistor, a current of 0.5 A flows through it. The internal resistance of the cell is $\_\_\_\_$ $\Omega$.

Question 3 · difficulty L2 · understanding

In an electrical circuit, a battery is connected to pass 20C of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at 15V. The workdone by the battery is __________J.

Question 4 · difficulty L2 · understanding

The battery of a mobile phone is rated as $4.2 \mathrm{~V}, 5800 \mathrm{~mAh}$. How much energy is stored ir it when fully charged?

• A. 87.7 kJ
• B. 43.8 kJ
• C. 48.7 kJ
• D. 24.4 kJ

Question 5 · difficulty L2 · understanding

Given below are two statements : Statement-I : The equivalent emf of two nonideal batteries connected in parallel is smaller than either of the two emfs. Statement-II : The equivalent internal resistance of two nonideal batteries connected in parallel is smaller than the internal resistance of either of the two batteries. In the light of the above statements, choose the correct answer from the options given below.

• A. Statement-I is false but Statement-II is true
• B. Statement-I is true but Statement-II is false
• C. Both Statement-I and Statement-II are false
• D. Both Statement-I and Statement-II are true

Question 6 · difficulty L2 · understanding

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

• A. 3 V
• B. 4 V
• C. 2 V
• D. 1.5 V

Question 7 · difficulty L2 · understanding

The combination of two identical cells, whether connected in series or parallel combination provides the same current through an external resistance of 2$$\Omega$$. The value of internal resistance of each cell is

• A. 2$$\Omega$$
• B. 4$$\Omega$$
• C. 6$$\Omega$$
• D. 8$$\Omega$$

Question 8 · difficulty L3 · understanding

Two cells of emfs 1 V and 2 V and internal resistance $2 \Omega$ and $1 \Omega$, respectively connected in parallel, gave a current of 1 A through an external resistance. If the polarity of one cell is reversed, then value of current through the external resistance will be $\frac{\alpha}{5} \mathrm{~A}$. The value of $\alpha$ is $\_\_\_\_$.

Question 9 · difficulty L3 · understanding

Two identical cells, when connected either in parallel or in series gives same current in an external resistance $$5 ~\Omega$$. The internal resistance of each cell will be ___________ $$\Omega$$.

Question 10 · difficulty L3 · understanding

Two cells are connected between points A and B as shown. Cell 1 has emf of 12 V and internal resistance of 3$$\Omega$$. Cell 2 has emf of 6V and internal resistance of 6$$\Omega$$. An external resistor R of 4$$\Omega$$ is connected across A and B. The current flowing through R will be ____________ A.