$$\begin{gathered} \mathrm{A} \mathrm{battery} \mathrm{of} \mathrm{internal} \mathrm{resistance} \mathrm{r}, \mathrm{when} \mathrm{connected} \mathrm{across} 2\mathrm{\Omega } \mathrm{resistor} \\ \mathrm{supplies} \mathrm{a} \mathrm{current} \mathrm{of} 4\mathrm{A}, \mathrm{when} \mathrm{the} \mathrm{same} \mathrm{battery} \mathrm{is} \mathrm{connected} \\ \mathrm{across} \mathrm{a} 5\mathrm{\Omega } \mathrm{resistor}, \mathrm{it} \mathrm{supplies} \mathrm{a} \mathrm{current} of 2\mathrm{A}. \mathrm{The} \mathrm{value} \mathrm{of} \mathrm{r} \mathrm{is} \end{gathered}$$

1.  $2\mathrm{\Omega }$

2.  $1\mathrm{\Omega }$

3.  $0.5\mathrm{\Omega }$

4.  $\mathrm{Zero}$

In the circuit shown in figure find the value of r(internal resistance of the cell) for which power transferred by the cell is maximum

1.  $4\mathrm{\Omega }$

2.  $12\mathrm{\Omega }$

3.  $16\mathrm{\Omega }$

4.  $8\mathrm{\Omega }$

If the voltage across a bulb decreases by 1%, then the percentage change in its power output is :

1.  1%

2.  4%

3.  2%

4.  5%

$$\begin{gathered} \mathrm{A} \mathrm{wire} \mathrm{having} \mathrm{resistance} 16\mathrm{\Omega } \mathrm{is} \mathrm{stretched} \mathrm{to} \mathrm{double} \mathrm{of} \mathrm{its} \mathrm{original} \mathrm{length}. \\ \mathrm{The} \mathrm{new} \mathrm{resistance} \mathrm{of} \mathrm{the} \mathrm{wire} \mathrm{will} \mathrm{be}: \end{gathered}$$

1.  $4\mathrm{\Omega }$

2.  $8\mathrm{\Omega }$

3.  $32\mathrm{\Omega }$

4.$64\mathrm{\Omega }$

In the circuit shown in the figure, the current supplied by the battery is

1.  2A

2.  1A

3.  0.5A

4.  0.4A

If a resistance coil is made by joining in parallel two resistances each of 20$\Omega$. An emf of 2V is applied across this coil for 100 seconds. The heat produced in the coil is

(1) 20 J

(2) 10 J

(3) 40 J

(4) 80 J

$$\begin{gathered} \mathrm{Two} \mathrm{battries} \mathrm{of} \mathrm{emf} {\mathrm{E}}_1, {\mathrm{E}}_2 \mathrm{and} \mathrm{internal} \mathrm{resistance} {\mathrm{r}}_1, {\mathrm{r}}_2 \mathrm{are} \mathrm{connected} in parallel. \\ \mathrm{The} \mathrm{effective} \mathrm{emf} \mathrm{of} \mathrm{the} \mathrm{circuit} \mathrm{across} \mathrm{A} \mathrm{and} \mathrm{B} \mathrm{is} \end{gathered}$$

1.  $\frac{{\mathrm{E}}_1{\mathrm{r}}_1 + {\mathrm{E}}_2{\mathrm{r}}_2}{{\mathrm{r}}_1 + {\mathrm{r}}_2}$

2.  $\frac{{\mathrm{E}}_1{\mathrm{r}}_2 + {\mathrm{E}}_2{\mathrm{r}}_1}{{\mathrm{r}}_1 + {\mathrm{r}}_2}$

3.  $\frac{{\mathrm{E}}_1{\mathrm{r}}_2 + {\mathrm{E}}_2{\mathrm{r}}_1}{{\mathrm{r}}_1 \times {\mathrm{r}}_2}$

4.  $\frac{{\mathrm{E}}_1{\mathrm{r}}_1 + {\mathrm{E}}_2{\mathrm{r}}_2}{{\mathrm{r}}_1 - {\mathrm{r}}_2}$

$$\begin{gathered} \mathrm{Which} \mathrm{of} \mathrm{the} \mathrm{following} \mathrm{graphs} \mathrm{correctly} \mathrm{represents} \mathrm{the} \mathrm{variation} \mathrm{of} \mathrm{mobility} \left(\mathrm{\mu }\right) \mathrm{of} \mathrm{electrons} \mathrm{with} \mathrm{applied} \\ \mathrm{electric} \mathrm{field} \left(E\right) \mathrm{in} \mathrm{a} \mathrm{metallic} \mathrm{conductor} ? \end{gathered}$$

1.  

2.  

3.  

4.  

The equivalent resistance across AB is :

1.  2R

2.  R/2

3.  4R/3

4.  3R/2

An electric Kettle draws 4.2A at 250V. How much time it would take to boil 1kg of water at $20°$C completely to ${100}^0 C$ ?

1.  320 seconds

2.  64 seconds

3.  3840 seconds

4.  960 seconds