- ADepends on the maximum area of the capacitor.
- BDepends on the maximum resistance offered.
- CDepends on the maximum electric field.
- DDepends on the maximum current passing through the capacitor.
Explanation:
The maximum energy that can be desirably stored in a capacitor is depends on the maximum electric field that the dielectric can withstand without breaking down. Therefore, capacitors of the same type have about the same maximum energy density, i.e. joules of energy per cubic meter.
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A 50 ohm galvanometer gets full scale deflection when a current of 0.01 A passes through the coil. When it is converted to a 10 A ammeter, the shunt resistance is
|
(a) 0.01 W |
(b) 0.05 W |
(c) 2000 W |
(d) 5000 W |
The fraction f of radioactive material that has decayed in time t, varies with time t. The correct variation is given by the curve

|
(a) A |
(b) B |
(c) C |
(d) D |
An electric kettle takes 4 A current at 220 V. How much time will it take to boil 1 kg of water from room temperature 20℃ ? The temperature of boiling water is 100℃
|
(a) 6.4 minutes |
(b) 6.3 minutes |
(c) 12.6 minutes |
(d) 12.8 minutes |
The energy of hydrogen atom in its ground state is – 13.6 eV. The energy of the level corresponding to the quantum number n is equal 5 is
|
(a) – 5.40 eV |
(b) – 2.72 eV |
(c) – 0.85 eV |
(d) – 0.54 eV |
$\vec{\text{v}},\ \vec{\text{v}}_1$ and $\vec{\text{v}}_2$ must be parallel to each other.
$\vec{\text{v}}_1+\vec{\text{v}}_2$ must be parallel to $\vec{\text{v}}.$
$\text{m}_1\vec{\text{v}}_1+\text{m}_2\vec{\text{v}}_2$ must be parallel to $\vec{\text{v}}.$
12 cells each having same emf are connected in series with some cells wrongly connected. The arrangement is connected in series with an ammeter and two cells which are in series. Current is 3 A when cells and battery aid each other and is 2 A when cells and battery oppose each other. The number of cells wrongly connected is
|
(a) 4 |
(b) 1 |
(c) 3 |
(d) 2 |
The momentum of the photon of wavelength 5000Å will be
|
(a) 1.3 |
(b) 1.3 |
|
(c) 4 |
(d) 4 |
An oxide coated filament is useful in vacuum tubes because essentially
|
(a) It has high melting point |
|
(b) It can withstand high temperatures |
|
(c) It has good machanical strength |
|
(d) It can emit electrons at relatively lower temperatures |