Three charged particles are initially in position-1. They are free to move and they come to position-2, after some time. Let U1 and U2 be the electrostatic potential energies in position-1 and 2 then
U1 = U2
U2 U1
U2 > U1
U1 > U2
D.
U1 > U2
The system of particles when left to themselves tend to move towards position where their potential energy is minimum.
Therefore, U2 < U1 or U1 > U2.
In L-R circuit the current increases to three - fourth of its maximum value in 4s, then the time constant of the circuit is
2 loge 2
The sensitiveness of a moving coil galvanometer can be increased by decreasing the
number of turns in the coils
area of the coil
magnetic field
couple per unit twist of the suspension
A potential difference V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, drift velocity
becomes two times
becomes half
does not change
becomes one-fourth
A steady current of 5 A is maintained for 45 min. During this time it deposits 4.572 g of zinc at the cathode of a voltmeter. ECE of zinc is
3.38 × 10-4 g/C
3.397 × 10-4 g/C
3.384 × 10-3 g/C
3.394 × 10-3 g/C
The earth's magnetic induction at a certain point is 7 x 10-5 Wb/m2. This is to be annuled by the magnetic induction at the centre of a circular conducting loop of radius 5 cm. The required current in the loop is
0.56 A
5.6 A
0.28 A
2.8 A
An astronomical telescope has a large aperture to
reduce spherical aberration
have high resolution
increase span of observation
have low dispersion
Which of the following is more close to a black body?
Black board paint
Green leaves
Black holes
Red roses