Current Electricity

The equivalent resistance of the following circuit is nearly

In a Wheatstone's bridge, three resistance 'Q', 'R' and 'S' are connected in three arms and first arm is formed by three resistances '$P_1$', '$P_2$' and '$P_3$' in parallel. The condition for the bridge to be balanced…

In Wheatstone bridge, resistance P is formed by a parallel combination of $p_1$ and $p_2$. The Q resistance is formed by a parallel combination of $q_1$ and $q_2$. The remaining two resistances are R and S respectively,…

In a Wheatstone's network $P \neq R$, the reading of the galvanometer is the same with a switch 'S' open or closed. Then

In a potentiometer experiment, the balancing with a cell is at length $240$ cm. On shunting the cell with a resistance of $2\ \Omega$, the balancing length becomes $120$ cm. The internal resistance of the cell is

In a Wheatstone's metre bridge, resistances $R$ and $S$ are connected in left and right gap, null point is obtained as $l$. After interchanging the resistances in the gaps, null point shifts to the left by $20$ cm. If…

A potentiometer wire of $400\ \text{cm}$ length has a resistance of $20\ \Omega$. It is connected in series with a resistance of $15\ \Omega$ and a accumulator of EMF $6\ \text{V}$ (negligible internal resistance). The…

The range of voltmeter is $10\ \text{V}$ and its resistance is $50\ \Omega$. To convert it to a voltmeter of range $15\ \text{V}$, how much resistance is to be added?

A resistance is to be measured using a meter bridge; the student chooses the standard resistance R to be $100\ \Omega$. The student finds the null point at $l_1=16$ cm. To get the null point near the middle of the wire,…

An unknown resistance wire in the left gap of a meter bridge balances a $10\ \Omega$ resistance in the right gap at a point that divides the bridge wire in a ratio $3:2$. If the length of this unknown resistance wire is…

When a galvanometer is shunted with a $2\ \Omega$ resistance, the deflection is reduced to one-fourth. If the galvanometer is further shunted with a $1\ \Omega$ resistance, the further reduction in deflection is a…

A galvanometer of resistance $90\ \Omega$ is shunted by a resistance of $10\ \Omega$. The fraction of main current that passes through shunt is