1
JEE Main 2022 (Online) 25th July Evening Shift
+4
-1

Capacitance of an isolated conducting sphere of radius R1 becomes n times when it is enclosed by a concentric conducting sphere of radius R2 connected to earth. The ratio of their radii $$\left( {{{{R_2}} \over {{R_1}}}} \right)$$ is :

A
$${n \over {n - 1}}$$
B
$${{2n} \over {2n + 1}}$$
C
$${{n + 1} \over n}$$
D
$${{2n + 1} \over n}$$
2
JEE Main 2022 (Online) 25th July Morning Shift
+4
-1

A condenser of $$2 \,\mu \mathrm{F}$$ capacitance is charged steadily from 0 to $$5 \,\mathrm{C}$$. Which of the following graph represents correctly the variation of potential difference $$(\mathrm{V})$$ across it's plates with respect to the charge $$(Q)$$ on the condenser?

A
B
C
D
3
JEE Main 2022 (Online) 30th June Morning Shift
+4
-1

Co is the capacitance of a parallel plate capacitor with air as a medium between the plates (as shown in Fig. 1). If half space between the plates is filled with a dielectric of relative permittivity $$\varepsilon$$r (as shown in Fig. 2), the new capacitance of the capacitor will be :

A
$${{{C_o}} \over 2}(1 + {\varepsilon _r})$$
B
$${C_o} + {\varepsilon _r}$$
C
$${{{C_o}{\varepsilon _r}} \over 2}$$
D
$${C_o}(1 + {\varepsilon _r})$$
4
JEE Main 2022 (Online) 29th June Evening Shift
+4
-1

A capacitor is discharging through a resistor R. Consider in time t1, the energy stored in the capacitor reduces to half of its initial value and in time t2, the charge stored reduces to one eighth of its initial value. The ratio t1/t2 will be

A
1/2
B
1/3
C
1/4
D
1/6
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