Two sound waves with wavelengths 5.0 m and 5.5 m respectively, each propagate in a gas with velocity 330 m/s. We expect the following number of beats per second
12
0
1
1
A transverse wave propagating along x-axis is represented by:
where x is in metres and t is in seconds. The speed of the wave is
The time of reverberation of a room A is one second. What will be the time (in seconds) of reverberation of a room, having all the dimensions double of those of room A?
2
4
Which one of the following statements is true?
Both light and sound waves in air are transverse
The sound waves in air are longitudinal while the light waves are transverse
Both light and sound waves in air are longitudinal
Both light and sound waves in air are longitudinal
In the circuit shown, if a conducting wire is connected between points A and B, the current in this wire will
flow from A to B
flow in the direction which will be decided by the value of V
be zero
be zero
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 necessarilyÂ
angle between  can have any value other thanÂ
angle between  can have any value othe than zero andÂ
angle between  can have any value othe than zero andÂ
Two cells, having the same emf, are connected in series through an external resistance R. Cells have internal resistances r1 and r2 (r1 > r2) respectively. When the circuit is closed, the potential difference across the first cell is zero, The value of R is
Two circular coils 1 and 2 are made from the same wire but the radius of the 1st coil is twice that of the 2nd coil. What is the ratio of potential difference applied across them so that the magnetic field at their centres is the same?
3
4
6
6
The core of a transformer is laminated because
energy losses due to eddy currents may be minimised
the weight of the transformer may be reduced
rusting of the core may be prevented
rusting of the core may be prevented
A.
energy losses due to eddy currents may be minimised
When magnetic flux linked with a coil changes, induced emf is produced in it and the induced current flows through the wire forming the coil. In 1895, Focault experimentally found that these induced currents are set up in the conductor in the form of closed loops. These current look like eddies or whirl pools and likewise are known as Focault's current. These current oppose the cause of their origin, therefore, due to eddy currents, a great amount of energy is wasted in form of heat energy. If core of transformer is laminated, then their effect can be minimised.
Two coils of self-inductances 2 mH and 8 mH are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is
10 mH
6 mH
4 mH
4 mH