NEET Physics Current Electricity MCQs

A variable resistor $R$ is connected across a battery of emf $E$ and internal resistance $r$. For what value of $R$ is the power delivered to $R$ maximum?

Two batteries with EMFs $E_1$ and $E_2$ and internal resistances $r_1$ and $r_2$ respectively are connected in parallel across a resistor R. The current through R is zero. Which of the following relations must hold true?

A potentiometer wire of length $L$ and resistance $R$ is connected to a battery of EMF $E$ and internal resistance $r$. A cell of EMF $E/2$ is balanced at a length $L/3$. What is the internal resistance of the cell?

A potentiometer wire of length 100 cm has a resistance of 10 Ω. It is connected in series with a resistance box and a 2V cell of negligible internal resistance. If a cell of emf $E_1$ is balanced against a length of 40 cm and another cell of emf $E_2$ is balanced against a length of 60 cm when the resistance in the box is 10 Ω and 5 Ω respectively, the ratio $\frac{E_1}{E_2}$ is:

A potentiometer wire AB is 100 cm long and has a total resistance of 10Ω. It is connected to a driver cell of emf E and internal resistance r. When a cell of emf $E_1$ is balanced against a length of $l_1$, the current through the potentiometer wire is $i_1$. When the cell $E_1$ is shunted by a resistance of 10Ω and balanced against a length $l_2$, the current through the potentiometer wire is $i_2$. Which of the following is true?

A potentiometer is being used to compare two cells of emfs $E_1$ and $E_2$. The balancing lengths are found to be $l_1$ and $l_2$ respectively. If a resistance R is connected across $E_2$, its balancing length changes to $l_3$. Which of the following relations must hold true?

Two cells of emf $E_1$ and $E_2$ and internal resistances $r_1$ and $r_2$ respectively are connected in parallel. The equivalent emf and internal resistance of the combination will be:

A potentiometer wire of length 100cm has a resistance of 10Ω. It is connected in series with a resistance R and a cell of emf 2V and negligible internal resistance. A source of emf 10mV is balanced against a length of 40cm of the potentiometer wire. What is the value of the resistance R?

A cell of emf E and internal resistance r is connected across a variable external resistance R. The graph of terminal potential difference V against current I reaches a maximum value of V. What is the relationship between E, r, and this maximum value of V?

n identical cells, each of emf E and internal resistance r, are connected in series to form a closed circuit. If one cell is reversed, what is the current in the circuit?