When the plane of the armature of an A.C. generator is parallel to the field in which it is rotating, then
In the Bohr's hydrogen atom model, the radius of the stationary orbit is directly propotional to n
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In photoelectric effect if the intensity of light is doubled then maximum kinetic energy of photoelectrons will become
A particle of mass m is executing uniform circular motion on a path of radius r. If p is the magnitude of its linear momentum. The radial force acting on the particle is
The resistance of a wire of uniform diameter d and lengths L is R. The resistance of another wire of the same material but diameter 2d and length 4L will be
A ball is allowed to fall from a height of 10 m. If there is 40% loss of energy due to impact, then after one impact ball will go up to
When a certain weight is suspended from a long uniform wire, its length increases by one cm. If the same material and length but having a diameter half of the first one then the increase in length will be
A capacitor of capacity C has reactance X. If capacitance and frequency become double, then reactance will be
The main function of coupling capacitor in and RC coupled common either amplifier is to:
Three capacitors each of capacity 4 μF are to be connected in such a way that their effective capacitance is 6 μF. This can be done by connecting
A van is moving with a speed of 72 kmph on a level road, where the coefficient of friction between its tyres and road is 0.5. The minimum radius of curvature, the road must have for safe driving of van is (g = 10ms−2 )
Temperature of water at the surface of lake is 20ºC. Then temperature of water just below the lower surface of ice layer is
The molar specific heat at constant pressure for a monoatomic gas is
The escape velocity on the earth is 11.2 kms−1 . The escape velocity on a planet of mass M/4 and radius R/2 is (M and R are the mass of earth and its radius)
A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 m/s. To give an initial upward acceleration of 20 m/s2, amount of gas ejected per second to supply needed thrust will be (g=10 m/s2)
The electric current in a circular coil of two turns produced a magnetic induction of 0.2T at its centre. The coil is unwound and is rewound into a circular coil of four turns. The magnetic induction at the centre of the coil now is, in tesla (if same current flows in the coil)
Two similar bar magnets of the same mass and dimensions freely suspended by threads in a horizontal plane are found to make 12 oscillations and 15 oscillations per minute. Then their magnetic moments are in the ratio of
If the radius of a soap bubble is four times that of another, then the ratio of their pressures will be
A body is moved along a straight line by a machine delivering constant power. The distance moved by the body in time t sec is proportional
A bullet is fired from a gun with a velocity of 1000 m−s⁻1 in order to hit a target 100 m away. At what height above the target should the gun be aimed? (Resistance of air is negligible and g = 10 m−s⁻1)
A palyer caught a cricket ball of mass 150 gm moving at a rate of 20 m/s. If the catching process be completed in 0.1 s, then the force of the blow exerted by the ball on the hands of the player is
If a simple pendulum oscillates with an amplitude of 50 mm and time period of 2 s, then its maximum velocity is
An aeroplane is flying at a constant horizontal velocity of 600 km/hr at an elevation of 6 km towards a point directly above the target on the earth's surface. At an appropriate time, the pilot releases a ball so that it strikes the target at the earth. The ball will appear to be falling
A satellite is in elliptical orbit about the earth (radius = 6400 km). At perigee it has an altitude of 1100 km and at the apogee its altitude is 4100 km. The major axis of the orbit is
Which of the following spectrum has high to low frequency range?
A particle performs uniform circular motion with an angular momentum L. If the angular frequency of the particle is doubled and kinetic energy is halved, its angular momentum becomes.
Consider the following statements about dimensions
P:Force=acceleration due to gravity * mass
Q:Electric charge=current * time
R:Magnetic flux=Electric voltage * time
The correct statements are :
Force necessary to pull a circular plate of 5 cm radius from water surface for which surface tension is 75 dynes/cm,is
The resistance of the filament of an electric bulb changes with temperature. If an electric bulb rated 220 volt and 100 watt is connected (220 x 0.8) volt sources, then the actual power would be
Density of a substance at 0ºC is 10gm/c.c and at 100º C its density is 9.7gm/c.c. The coefficient of linear expansion of the substance is