A solid metal sphere of radius 50 cm carries a charge 25 x 10-10 C, The electrostatic potential at a distance of 20 cm from the centre will be :
25 V
15 V
35 V
45 V
Two plates (area = S) charged to + q1 and + q2 (q2 <q1)are brought closer to form a capacitor of capacitance C. The potential difference across the plates is :
What is the drift velocity of electrons if the current flowing through a copper wire of 1 mm diameter is 1.1 A. Assume that each atom of copper contributes one electron : (Given: density of Cu = 9 g/cm3 and atomic weight of Cu = 63)
0.3 mm/s
0.5 mm/s
0.1 mm/s
0.2 mm/s
A uniform magnetic field is at a right angle to the direction of motion of proton. As a result, the proton describes a circular path of radius 2.5 cm. If the speed of proton is doubled then the radius of the circular path will be :
0.5 cm
2.5 cm
5.0 cm
7.5 cm
An electron accelerated through a potential difference enters into a uniform transverse magnetic field and experience a force F. If the accelerating potential is increased to 2V, the electron in the same magnetic field will experience a force :
F
F/2
2F
C.
Force F = evB
F2 =
The certain amount of current when flowing in a properly set tangent galvanometer produces a deflection of 45°. The current be reduced by a factor of ✓3, the deflection would :
decrease by 30°
decrease by 15°
increase by 15°
increase by 30°
If a current of 3 A fl.owing in the primary coil is reduced to zero in 0.01 s then the induced emf in the secondary coil is 1500 V, the mutual inductance between the two coils is :
0.5 H
5 H
1.5 H
10 H
In order to obtain time constant of 10 s in an RC circuit containing a resistance of 103Ω, the capacity of the condenser should be :
10 μF
100 μF
1000 μF
10000 μF
An a-particle, when accelerated through a potential difference of V volt, has a wavelength λ associated with it. In order to have the same λ, by what potential difference a proton must be accelerated?
8 V
6 V
4 V
12 V
What is the angle between the electric dipole moment and the electric field strength due to it on the equatorial line?
0°
90°
180°
None of these