The capacity of an air condenser is 2.0 µF. If a medium is placed between its plates, the capacity becomes 12 μF. The
dielectric constant of the medium will be
5
4
3
6
Taking the earth to be a spherical conductor of diameter 12.8×103 km. Its capacity will be
711 μF
611 μF
811 μF
511 μF
A charge Q is distributed uniformly in a sphere (solid). Then, the electric field at any point r, where, r < R (r is the radius of sphere) varies as:
r -1
r
r -2
As per this diagram a point charge +q is placed at the origin O. Work done in taking another point charge -Q from the point A [coordinates (O, a)] to another point B [coordinates (a, O)] along the straight path AB is
zero
A charged particle (charge q) is moving in a circle of radius R with uniform speed v. The associated magnetic moments given by
qνR2
qνR
A steady current of 1.5 A flows through a copper voltameter for 10 min. If the electrochemical equivalent of copper is 30x 10-5 g C-1 , the mass of copper deposited on the electrode will be
0.40 g
0.50 g
0.67 g
0.27 g
When a charged particle moving with velocity is subjected to a magnetic field of induction , the force on it is non- zero. This implies that
angle between is necessarily 90o
angle between can have any value other than 90o
angle between can have any value other than 180o
angle between is either zero or 180o
What is not true for equipotential surface for uniform electric field?
Equipotential surface is flat
Equipotential surface is spherical
Electric lines are perpendicular to equipotential surface
Work done is zero
A capacitor having capacitance 1 uF with air, is filled with two dielectrics as shown. How many times capacitance will increase
12
6
8/3
3
B.
6
After filling with dielectrics the two capacitors will be in parallel order. As shown, the two capacitors are connected in parallel. Initially the capacitance of capacitor
C = ε0A/d
where A is area of each plate and d is the separation between the plates.
After filling with dielectrics, we have two capacitors of capacitance.
Hence, their equivalent capacitance
Ceq = C1 + C2
= 4C +2C
C = 6C
ie, new capacitance will be six times of the original.
Figure shows three spherical and equipotential surfaces A, B and C round a point charge q. The potential difference If t1 and t2 be the distances between them, then
t1 = t2
t1 > t2
t1 < t2
t1 ≤ t2