A certain current on passing through a galvanometer produces a deflection of 100 divisions. When a shunt of one ohm is connected, the deflection reduces to 1 division. The galvanometer resistance is
100 W
99 W
10 W
9.9 W
A closed organ pipe and an open organ pipe of same length produce 2 beats/second while vibrating in their fundamental modes. The length of the open organ pipe is halved and that of closed pipe is doubled. Then, the number of beats produced per second while vibrating in the fundamental mode is ______.
8
7
2
6
A convex and a concave lens seperated by distance d are then put in contact. The focal length of the combination
decreases
increases
becomes 0
remains the same
A current of 5A is flowing at 220 V in the primary coil of a transformer. If the voltage produced in the secondary coil is 2200 V and 50% of power is lost, then the current in the secondary will be
2.5 A
5 A
0.25 A
0.5 A
A fish in water (refractive index n) looks at a bird vertically above in the air. If y is the height of the bird and x is the depth of the fish from the surface, then the distance of the bird as estimated by the fish is
x + ny
A horizontal metal wire is carrying an electric current from the north to the south. Using a uniform magnetic field, it is to be prevented from falling under gravity. The direction of this magnetic field should be towards the______.
east
west
north
south
A mass of 10 kg is suspended from a spring balance. It is pulled aside by a horizontal string so that it makes an angle of` 600 with the vertical. The new reading of the balance is
20 kg.wt
10 kg.wt
kg.wt
kg.wt
A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it
increases, thermal velocity of the electron decreases
decreases, thermal velocity of the electron decreases
increases, thermal velocity of the electron increases
decreases, thermal velocity of the electron increases
A motorboat covers a given distance in 6 hours moving downstream on a river. It covers the same distance in 10 hours moving upstream. The time it takes to cover the same distance in still water is ______.
6.5 hours
8 hours
9hours
7.5 hours
A radioactive sample S1 having the activity A1 has twice the number of nuclei as another sample S2 of activity A2. If A2 = 2A1, then the ratio of half life of S1 to the half life of S2 is
0.25
0.75
4
2
A body of mass M hits normally a rigid wall with velocity V and bounces back with the same velocity. The impulse experienced by the body is
Zero
MV
1.5 MV
2 MV
A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest
At the instant just after the body is projected
At the highest position of the body
At the instant just before the body hits the earth
It remains constant all through
A charge Q is enclosed by a Gaussian spherical surface of radius R. If the radius is doubled, then the outward electric flux will
Be doubled
Increase four times
Be reduced to half
Remain the same
A convex lens of focal length 30 cm produces 5 times magnified real image of an object. What is the object distance?
36 cm
25 cm
30 cm
150 cm
A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half-life of the source is _______.
kg.wt
kg.wt