Figure below shows four plates each of area A and separated from one another by a distance d. What is the capacitance between P and Q ?
A soap bubble is charged to a potential of 16 V. Its radius is, then doubled. The potential of the bubble now will be
16 V
8 V
4 V
2 V
A parallel plate capacitor of capacitance 10 F is charged to 1 µC. The charging battery is removed and then the separation between the plates is doubled. Work done during the process is
5 mJ
0.05 mJ
1 mJ
10 mJ
C.
1 mJ
C = 10 μF = 1 μC
Therefore, work done = 1 mJ
In which of the following substances does resistance decrease with increase in temperature ?
Copper
Carbon
Constantant
Silver
Resistors P and Q are connected in the gaps of the meter bridge. The balancing point is obtained from the zero end. If a 6 Ω resistance is connected in series with P the balance point shifts to m from the same end. P and Q are
4, 2
2, 4
both (a) and (b)
neither (a) nor (b)
The currents i1 and i2 through the resistors R1 (= 10 Ω) and R2 (= 30 Ω) in the circuit diagram with E1 =3V, E2 = 3V and E3 = 2V are respectively
0.2 A, 0.1 A
0.4 A, 0.2 A
0.1 A, 0.2 A
0.2 A, 0.4 A
An α-particle with a specific charge of 2.5 × 107 C kg-1 moves with a speed of 2 x 105 ms-1 in a perpendicular magnetic field of 0.05 T. Then the radius of the circular path described by it is
8 cm
4 cm
16 cm
2 cm
The magnitude of the earth's magnetic field at a place is B0 and the angle of dip is δ. A horizontal conductor of length l lying magnetic north-south moves eastwards with a velocity v. The emf induced across the conductor is
zero
B0 lv sin δ
B0 lv
B0 lv cos δ
A milliammeter of range 0- 30 mA has internal resistance of 20 Ω. The resistance to be connected in series to convert it into a voltmeter of maximum reading 3V is
49 Ω
80 Ω
40 Ω
30 Ω