Three equal charges, each having a magnitude of 2.0 x 10-6 C, are placed at the three corners of a right angled triangle of sides 3 cm, 4 cm and 5 cm. The force (in magnitude) on the charge at the right angled corner is
50 N
26 N
29 N
45.9 N
The parts of two concentric circular arcs joined by two radial lines and carries current i. The arcs subtend an angle 0 at the centre of the circle. The magnetic field at the centre O, is
The ammeter shown in figure consists of a 480 Ω coil connected in parallel to a 20 Ω shunt. The reading of ammeter is
0.125 A
1.67 A
0.13 A
0.67 A
An inductor (L = 20 H), a resistor (R = 100 Ω) and a battery (E = 10 V) are connected in series. After a long time, the circuit is short-circuited and then the battery is disconnected. Find the current in the circuit at 1 ms after short circuiting.
4.5 x 105 A
3.2x 10-5 A
9.8 × 10-5 A
6.7 × 10-4 A
Two charges of + 10 μC and +20 μC are separated by a distance 2 cm. The net potential (electric) due to the pair at the middle point of the line joining the two changes, is
27 MV
18 MV
20 MV
23 MV
A copper rod of length 20 cm and cross-sectional area 2 mm is joined with a similar aluminium rod as shown below
The resistance of pair of rods is (ρAl =2.6 x 10-8 Ω-m and ρCu =1.7 x 10-8 Ω-m)
1.0 mΩ
2.0 mΩ
3.0 mΩ
None of these
A square loop is made by a uniform conductor wire as shown in figure
The net magnetic field at the centre of the loop if side length of the square is a
zero
None of these
B.
zero
The current will be equally divided at junction P. The field at the centre due to wires PQ and SR will be equal in magnitude but opposite in the direction, so its effective field will be zero. Similarly, net field due to wires PS and QR is zero. Therefore, the net field at the centre of the loop is zero.
The electron of H - atom is revolving around the nucleus in circular orbit having radius with . The current produced due to the motion of electron is
zero
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