1. Electric charges and fields - CBSE STD 12 Science Physics Questions

725

Questions

1

Question groups

5

Question types

01

M.C.Q (1 Marks)

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Sample Questions

1. Electric charges and fields questions

One sample from each question group in this chapter. Select any group above to see the full set with answer keys.

Q 1M.C.Q (1 Marks)1 Mark

If $\oint_s \vec{E} \cdot \overrightarrow{d S}=0$ over a surface, then:

A
the electric field inside the surface is necessarily uniform.
✓
the number of flux lines entering the surface must be equal to the number of flux lines leaving it.
C
the magnitude of electric field on the surface is constant.
D
all the charges must necessarily be inside the surface.

Answer: B.

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Q 2M.C.Q (1 Marks)1 Mark

An electric dipole is placed at an angle of $30^{\circ}$ with an electric field of intensity $2 \times 10^5\,NC ^{-1}$. It experiences a torque equal to $4\,Nm$. Calculate the magnitude of charge on the dipole, if the dipole length is $2\,cm$.

✓
$2\,mC$
B
$8\,mC$
C
$6\,mC$
D
$4\,mC$

Answer: A.

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Q 3M.C.Q (1 Marks)1 Mark

The ratio of coulomb's electrostatic force to the gravitational force between an electron and a proton separated by some distance is $2.4 \times 10^{39}$. The ratio of the proportionality constant, $K=\frac{1}{4 \pi \varepsilon_0}$ to the Gravitational constant $G$ is nearly (Given that the charge of the proton and electron each $=1.6 \times 10^{-19}\; C$, the mass of the electron $=9.11 \times 10^{-31}\; kg$, the mass of the proton $=1.67 \times 10^{-27}\,kg$ ):