A transformer is employed to reduce 220 V to 11 V. The primary draws a current of 5 A and the secondary 90 A. The efficiency of the transformer is
A system consists of two identical particles one particle is at rest and the other particle has an acceleration 'a'. The centre of mass of the system has an acceleration of
Two resistances of 400 Ω and 800 Ω are connected in series with 6 volt battery of negligible internal resistance. A voltmeter of resistance 10,000 Ω is used to measure the potential difference across 400 Ω. The error in the measurement of potential difference in volts approximately is
The core of a transformer is laminated so that
The de-Broglie wavelength associated with proton changes by 0.25% if its momentum is changed by P₀. The initial momentum was
A horizontal force, just sufficient to move a body of mass 4kg lying on a rough horizontal surface is applied on it. The coefficients of static and kinetic friction between the body and the surface are 0.8 and 0.6 respectively. If the force continues to act even after the block has started moving, the acceleration of the block in m s−2 is [g = 10 m s − 2 ]
A capacitor of capacity 10 μ F is charged to 40V and a second capacitor of capacity 15 μ F is charged to 30V. If they are connected in parallel the amount of charge that flows from the smaller capacitor to higher capacitor in μ C is
The earth radiates in the infra-red region of the spectrum. The spectrum is correctly given by
Wien's law states that when the temperature of a black body radiator increases, the overall radiated energy increases and the peak of the radiation curve moves to shorter wavelengths.
If an electron revolve in the path of a circle of radius of 0.5 x 10 − 10 m at a frequency of 5 x 10 5 cycles/sec. The electric current in the circle is (charge of an electron = 1.6 x 10−19 C)
A bus is moving with a speed of 10 ms−1 on a straight road. A scooterist wishes to overtake the bus in 100 s. If the bus is at a distance of 1 km from the scooterist, with what speed should the scooterist chase the bus?
Two stones are projected with the same speed but making different angles with the horizontal. Their horizontal ranges are equal. The angle of projection of one is π/3 and the maximum height reached by it is 102 m. Then the maximum height reached by the other in metre is
A 5000 kg rocket is set for vertical firing. The exhaust speed is 800 ms⁻1. To give an initial upward accleration of 20 ms⁻2. the amount of gas ejected per second to supply the needed thrust will be (g=10 ms⁻2)
The M.I. of a body about the given axis is 1.2 kg m2 initially the body is at rest. In order to produce a rotational kinetic energy of 1500 joule an angular acceleration of 25 rad/sec2 must be applied about that axis for a duration of
Two projectiles are fired at different angles with the same magnitude of velocity, such that they have the same range. At what angles they might have been projected?
For equal range, the particle should either be projected at an angle θ or (90 - θ)
The dimensional formula M0L2T-2 stands for
Latent heat = Energy/Mass = M0L2T-2
Two voltmeters, one of copper and the other of silver, are joined in parallel. When a total charge q flows through the voltmeters, equal amount of metals are deposited on their respective cathodes. If the electrochemical equivalents of copper and silver are z1 and z2 respectively, then charge which flows through the silver voltmeter is
540 g of ice at 0oC is mixed with 540 g of water at 80oC. The final temp. of the mixture in oC will be
Water falls from a height of 210 m. Assuming whole of energy due to fall is converted into heat the rise in temperature of water would be (J = 4.3 Joule/cal)
The dimensions of electrical resistance are
Since according to Ohm's Law :
From the above equation