In Wheatstone network, P = 2 Ω, Q = 2 Ω, R = 2 Ω and S = 3 Ω. The resistance with which S is to be shunted in order that the bridge may be balanced is
4 Ω
1 Ω
6 Ω
2 Ω
Core of electromagnets are made of ferromagnetic material which has
low permeability and high retentivity
high permeability and low retentivity
low permeability and low retentivity
high permeability and high retentivity
Two parallel wires 1 m apart carry currents of 1 A and 3 A respectively in opposite directions. The force per unit length acting between two wires is
6 × 10-5 Nm-1 repulsive
6 × 10-7 Nm-1 repulsive
6 × 10-5 Nm-1 attractive
6 × 10-7 Nm-1 attractive
A galvanometer of resistance 50 Ω gives a full scale deflection for a current 5 x 10-4 A. The resistance that should be connected in series with the galvanometer to read 3 V is
5059 Ω
595 Ω
5950 Ω
5050 Ω
A cyclotron is used to accelerate
only negatively charged particles
neutron
both positively and negatively charged particles
only positively charged particles
D.
only positively charged particles
As, electrons cannot be accelerated in a cyclotron A large increase in their energy increases their velocity to a very large extent. This throws the electrons out of step with the oscillating field whlle, neutron being electrically neutral, cannot be accelerated in a cyclotron. So, cyclotron is used to accelerate only positively charged particle.
A transformeris used to light 100 W -110 V lamp from 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is
96 %
90 %
99 %
95 %
In an L-C-R circuit, at resonance
the current is minimum
the current and voltage are in phase
the current leads the voltage by
the impedance is maximum
An aircraft with a wingspan of 40 m flies with a speed of 1080 km/h in the Eastward direction at a constant altitude in the Northern hemisphere, where the vertical component of the Earth's magnetic field is 1.75 × 10-5 T. Then the emf developed between the tips of the wings is
0.21 V
0.5 V
2.1 V
0.34 V
Two coils have a mutual inductance 0.005 H. The current changes in the first coil according to the equation I = im sin ωt, where im = 10 A and ω = 100 rad s-1. The maximum value of the emf induced in the second coil is
The magnetic susceptibility of a paramagnetic material at -73°C is 0.0075 and its value at − 173°C will be
0.015
0.0045
0.0075
0.0030