An electron having charge \(e\) and mass \(m\) is moving in a uniform electric field \(E.\) Its acceleration will be:
1. \(\frac{e^2}{m}\)
2. \(\frac{E^2e}{m}\)
3. \(\frac{eE}{m}\)
4. \(\frac{mE}{e}\)
Infinite charges of magnitude q each are lying at x =1, 2, 4, 8... meter on X-axis. The value of the intensity of the electric field at point x = 0 due to these charges will be
(1) 12 × 109q N/C
(2) Zero
(3) 6 × 109q N/C
(4) 4 × 109q N/C
A pendulum bob of mass and carrying a charge is at rest in a horizontal uniform electric field of 20000 V/m. The tension in the thread of the pendulum is
(1)
(2)
(3)
(4)
A charged ball \(B\) hangs from a silk thread \(S,\) which makes an angle \(\theta\) with a large charged conducting sheet \(P,\) as shown in the figure. The surface charge density \(\sigma\) of the sheet is proportional to:
1. \(\sin\theta\)
2. \(\tan\theta\)
3. \(\cos\theta\)
4. \(\cot\theta\)
Two-point charges +8q and –2q are located at x = 0 and x = L respectively. The location of a point on the x-axis at which the net electric field due to these two point charges is zero is
1. 8 L
2. 4 L
3. 2 L
4.
Three infinitely long charge sheets are placed as shown in the figure. The electric field at point P is
(1)
(2)
(3)
(4)
Four-point +ve charges of the same magnitude (Q) are placed at four corners of a rigid square frame as shown in the figure. The plane of the frame is perpendicular to Z-axis. If a –ve point charge is placed at a distance z away from the above frame (z<<L) then
1. – ve charge oscillates along the Z-axis.
2. It moves away from the frame.
3. It moves slowly towards the frame and stays in the plane of the frame.
4. It passes through the frame only once.
A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by
(1)
(2)
(3)
(4) Zero
Electric field at a point varies as r0 for
(1) An electric dipole
(2) A point charge
(3) A plane infinite sheet of charge
(4) A line charge of infinite length