The capacitance of earth, viewed as a spherical conductor of radius 6408 km is:
(a) 1420 μF
(b) 712 μF
(c) 680 μF
(d) 540 μF
The charges on two spheres are +7mC and –5mC respectively. They experience a force F. If each of them is given an additional charge of –2mC, the new force of attraction will be
The colours on the soap bubble is due to
(a) Interference
(b) Diffraction
(c) Polarisation
(d) Reflection
The electric potential due to point charge 3 nC at distance of 9 cm is
(a) 270 v
(b) 3 v
(c) 300 v
(d) 30 v
The electric potential of earth is taken as:
(a) zero
(b) infinity
(c) unity
(d) None of these
The electric potential of earth is taken to be zero, because earth is a good
(a) insulator
(b) conductor
(c) semiconductor
(d) dielectric
The electric potential V at any point (x,y,z) all in meters in space is given by V=4x2 volts. The electric field at the point (1,0,2) in volt/meter is
1. 8 along negative X axis
2. 8 along positive X axis
3. 16 along negative X axis
4. 16 along positive X axis
The electrostatic potential energy between proton and electron separated by a distance of 1 Å is
(a) 13.6eV
(b) 27.2eV
(c) -14.4eV
(d) 1.44eV
The magnetic field at an outside point due to a long straight conductor carrying a constant current(I) is independent of
a) Material of the conductor
b) Radius of the conductor
c) Both (a) and (b)
d) Neither (a) nor (b)
The potential energy of a charged parallel plate capacitor is \(U_0\). If a slab of dielectric constant K is inserted between the plates, then new potential energy will be
(a) \(U_0\)/K
(b) \(U_0\)K²
(c) \(U_0\)/K²
(d) \(U_0\)²
Three capacitors 3 μF, 6 μF and 6 μF are connected in series to a source of 120 volt. The potential difference across the 3 μF capacitor will be
(a) 40 volt
(b) 30 volt
(c) 40 volt
(d) 60 volt
Three capacitors of 6μf each are connected across a triangle. What is the resultant capacitance across any side of the triangle.
1. 6 μf
2. 2 μf
3. 4 μf
4. 12μf
Three charges each equal to 2 μC are placed at the corners of an equilateral triangle. If force between any two charges is 2F, then the net force on either will be:
To observe diffraction, the size of the obstacle
(a) should be X/2, where X is the wavelength.
(b) should be of the order of wavelength.
(c) has no relation to wavelength.
(d) should be much larger than the wavelength.
Two capacitors of 3 μF and 6 μF are connected in series with a battery of P.d. 12 V. The P.d. across 3μF and 6μF capacitors respectively will be :
(a) 8 V, 4 V
(b) 6 V, 6 V
(c) 4 V, 8 V
(d) 9 V, 3 V