J J Science Academy - Test Paper

1. A resistance carries a current of 2 A . When its ends are connected to a copper wire, of negligible resistance, i.e. when it is short circuited, then current through it will be

(1) 2 A

2. In the given figure, $V_{1}$ is

(1) $\frac{200}{3} V$
(2) $\frac{100}{3} V$
(3) $\frac{50}{3} V$
(4) 50 V

3. In the given figure, current through $6 \Omega$ is

(1) 1.5 A
(2) 1.2 A
(3) 0.8 A
(4) 1.8 A

4. In the given figure, applied voltage V is (All resistances are in $\Omega$ )

(1) 35 V
(2) 45 V
(3) 50 V
(4) 55 V

5. Current through $40 \Omega$, $60 \Omega$ and $20 \Omega$ resistance, respectively

(1) 6 A each
(2) 2 A each
(3) $6 A, 4 A, 12 A$
(4) $12 A, 4 A, 6 A$

6. Two resistors, $X$ and $Y$, having resistances $R$ each, are connected in series across a potential difference $V$. When a resistance R is connected in parallel to Y , the percentage change in the potential difference across it will be

(1) $17 \%$
(2) $25 \%$
(3) $-17 \%$
(4) $-25 \%$

7. To use a bulb, rated at $20 V, 6 W$, with a 200 V source, you have to connect a resistance

(1) in parallel with the bulb.
(2) in series with the bulb.
(3) in series or in parallel with the bulb.
(4) none of the above

8. In the accompanying circuit, if the resistance of $R_{2}$ is decreased, then

(1) the current through $R_{1}$ increases.
(2) the current through $R_{1}$ remains constant.
(3) the voltage drop across $R_{2}$ decreases.
(4) the power dissipated by $R_{2}$ decreases.

9. Three conductors draw currents of $1 A, 2 A$ and 3 A respectively when connected in turn across a battery. If the series combination of them is connected across the same battery, the current drawn will be

(1) 5 A
(2) >1 A but < 2 A
(3) < 1 A
(4) $\frac{5}{7} A$

10. If the current I in the given circuit is 0.1 A , then $R=$

(1) $3 \Omega$ $30 \Omega$
(2) $30 \Omega$
(3) $60 \Omega$
(4) $300 \Omega$

11. In the circuit shown below, the total resistance of the circuit between points $P$ and $Q$ is also equal to $R$. The value of the unknown resistor $R$ is

(1) $3 \Omega$
(2) $\sqrt{39} \Omega$
(3) $\sqrt{69} \Omega$
(4) $10 \Omega$

12. The current through the $4 \Omega$ resistor is

(1) 0.5 A
(2) 0.4 A
(3) 3 A
(4) 0.3 A

13. Two resistors P and $Q(P>Q)$ are connected in series as shown in figure. With the usual symbols, which of the following is NOT true?

(1) $V_{AB}>V_{BC}$
(2) $V_{C}
(3) $I_{1}=I_{2}=I_{3}$
(4) $V_{B}>V_{A}$

14. Three voltmeters $A, B$ and C having resistances $R, \frac{3}{2} R$ and 3 R respectively are X - (A) connected as shown in the figure. When some potential difference is applied between X and Y , the respective voltmeter readings are $V_{A}, V_{B}$ and $V_{C}$. Then

(1) $V_{A} \neq V_{B}=V_{C}$
(2) $V_{A} \neq V_{B} \neq V_{C}$
(3) $V_{A}=V_{B} \neq V_{C}$
(4) $V_{A}=V_{B}=V_{C}$