1
GATE ECE 2017 Set 2
Numerical
+2
-0
An electron (q1) is moving in free space with velocity 105 m/s towards a stationary electron (q2) far away. The closest distance that this moving electron gets to the stationary electron before the repulsive force diverts its path is ___________ ×10-8m.

[Given, mass of electron m = 9.11×10-31 kg, charge of electron e = -1.6×10-19 C , and permittivity $$\varepsilon_0=\left(1/36\mathrm\pi\right)\times10^{-9}\;\mathrm F/\mathrm m$$].

2
GATE ECE 2016 Set 2
+2
-0.6
The parallel-plate capacitor shown in the figure has movable plates. The capacitor is charged so that the energy stored in it is E when the plate separation is d. The capacitor is then isolated electrically and the plates are moved such that the plate separation becomes 2d. At this new plate separation, what is the energy stored in the capacitor, neglecting fringing effects?

A
2E
B
$$\sqrt2\mathrm E$$
C
E
D
E/2
3
GATE ECE 2015 Set 3
Numerical
+2
-0
A coaxial capacitor of inner radius 1 mm and outer radius 5 mm has a capacitance per unit length of 172 pF/m. If the ratio of outer radius to inner is doubled, the capacitance per unit length (in pF/m) is _____.
4
GATE ECE 2014 Set 4
+2
-0.6
If $$\overrightarrow{\mathrm E}=-\left(2\mathrm y^2\;-3\mathrm{yz}^2\right)\widehat{\mathrm x}\;-\left(6\mathrm{xy}^2-3\mathrm{xz}^2\right)\widehat{\mathrm y}+\left(6\mathrm{xyz}\right)\widehat{\mathrm z}$$

is the electric field in a source free region, a valid expression for the electrostatic potential is

A
xy3 - yz2
B
2xy3 - xyz2
C
y3 + xyz2
D
2xy3 - 3xyz2
GATE ECE Subjects
Network Theory
Control Systems
Electronic Devices and VLSI
Analog Circuits
Digital Circuits
Microprocessors
Signals and Systems
Communications
Electromagnetics
General Aptitude
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