In the circuit shown below, a student performing Ohm's law experiment accidentally connects the voltmeter and the ammeter as shown. The reading in the voltmeter will be close to .......... $V$.

In the given circuit,$E_1 = E_2 = E_3 = 2 \, V$ and $R_1 = R_2 = 4 \, \Omega$. What is the current flowing between points $A$ and $B$ (in $, A$)?

$A$ bulb with a rating of $4.5 \, W, 1.5 \, V$ is connected as shown in the figure. To make the bulb glow at full brightness,the $e.m.f.$ of the cell should be ................ $V$.

The potential difference across the $8\ \Omega$ resistance is $48\ V$ as shown in the figure. The value of the potential difference across points $X$ and $Y$ will be ............... $V$.

Consider the two circuits $P$ and $Q$ shown below,which are used to measure the unknown resistance $R$. In each case,the resistance is estimated by using Ohm's law $R_{\text{est}} = \frac{V}{I}$,where $V$ and $I$ are the readings of the voltmeter and the ammeter,respectively. The meter resistances $R_V$ and $R_A$ are such that $R_A \ll R \ll R_V$. The internal resistance of the battery may be ignored. The absolute error in the estimate of the resistance is denoted by $\delta R = |R - R_{\text{est}}|$.
$(a)$ Express $\delta R_P$ in terms of the given resistance values.
$(b)$ Express $\delta R_Q$ in terms of the given resistance values.
$(c)$ For what value of $R$ will $\delta R_P \approx \delta R_Q$?

The reading of the voltmeter in the circuit shown is ............. $V$. (in $.25$)