CBSE
Three capacitors of capacitances 1 µF, 2µF and 4μF are connected first in a series combination and then in a parallel combination. The ratio their equivalent capacitances will be
2 : 49
49 : 2
4 : 49
49 : 4
A charged particle is accelerated by a potential of 200 V. If its velocity is 8.4 × 108 m/s, then value of e/m for that particle is
17.6 × 1016
14.5 × 1012
1.76 × 1015
1.45 × 1015
Two small balls, each carrying a charge q are suspended by equal insulator strings of length l m from the hook of a stand. This arrangement is carried in a satellite in space. The tension in each string will be
Electric field at point 20 cm away from the centre of dielectric sphere is 100 V/m, radius of sphere is 10 cm, then the value of electric field at a distance 3 cm from the centre is
100 V/m
125 V/m
120 V/m
0
If V =ary, then electric field at a point will be proportional to
r
r -1
r -2
r2
Two capacitors of capacities C1 and C2 are charged upto the potential V1 and V2 then condition for not flowing the charge between on connected them in parallel is
C1 = C2
C1V1 = C2V2
V1 =V2
A parallel palte condenser is filled with two dielectrics as shown in figure. Area of each pate is A m2 and the separation is d metre. The dielectric constants are K1 and K2 respectively. Its capacitance in farad will be
Magnetic field of the earth is H =0.3 g. A magnet is vibrating 5 oscillations per min then the dippreciation required in the magnetic field of the earth of increase time period upto 10 oscillations per minute is
2.25 g
0.6 g
0.9 g
0.12 g
A parallel plate capacitor with air as the dielectric has capacitance C. A slab of dielectric constant K and having the same thickness as the separation between the plates is introduced so as to fill one-fourth of the capacitor as shown in the figure. The new capacitance will be
Two equal negative charges - q are fixed at the point (0, a) and (0, - a) on the y-axis. A positive charge Q is released from rest at the point (2a, 0) on the x-axis. The charge wil
execute SHM about the origin
move to the origin and remain at rest
move to infinity
execute oscillatory but not SHM