The resistance of hot tungsten filament is about 10 times the cold resistance. What will be the resistance of 100 Ω and 200 V lamp, when not in use?
If two atoms have their atomic numbers as z1 and z2 , the ratio of the wavelengths λ1 and λ2 corresponding to their K α lines is
A potential difference of V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, drift velocity
A spherical ball contracts in volume by 0.01% when subjected to a normal uniform pressure of 100 atmospheres. The bulk modulus of its material in dyne/cm2 is
A 220 V, 50 Hz a.c. source is connected to an inductance of 0.2 H and a resistance of 2 Ω in series. What is current in the circuit ?
Minimum no. of 8 μF and 250 V capacitors, used to make a combination of 16 μF and 1000 V, is
The value of g on the earth's surface is 980 cm/sec2. Its value at a height of 64 km from the earth's surface is
A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is 6 m−s⁻1. The kinetic energy of the other mass is
The Torque acting on a current carrying coil placed in a magnetic field is given by
A galvanometer of range 10 mA has a coil of resistance 1 Ω. To use it as a voltmeter of range 10 V, the resistance that must be connected in series with it, is
The magnetic lines of force inside a bar magnet
By which velocity a ball be projected vertically so that the distance covered by it in 5th second is twice the distance it covers in its 6th second (g=10 m/s2)
Two equal charges q each are placed at a distance of 2a. If a third charge-2q is placed at the mid-point, then potential energy of the system is
A coin, placed on a rotating turn-table slips, when it is placed at a distance of 9 cm from the centre. If angular velocity of the turn-table is trippled, it will just slip if its distance from the centre is
Which of the following is an example of motion in three dimensions?
The nucleus of 56Ba141 contains ---- neutrons
A U-tube contains water and methylated spirit seperated by mercury. The mercury columns in the two arms are in level with 18 cm of water in one arm and 20 cm spirit in the other arm. The density of spirit is (Density of water=1 g-cm-3)
For water column in one arm of U - tube
h1 = 18 cm, ρ1 = 1 gm cm-3
For spint column in other arm of U - tube
h2 18 cm, ρ2 = ?
If P1 and P2 be the pressures exerted by water column and spirit column respectively
Then P1 = h1 ρ1 g
and P2 = h2 ρ2 g
The mercury columns in the two arms of U-tube are at the same level, thus in equilibrium
P1 = P2
or h1 ρ1 g = h2 ρ2 g
The length of second pendulum on the earth where g is 9.8 m/s2 is 1m. The length of a second pendulum on aplanet where = 4.9 m/s2 will be
A particle is viberating in a simple harmonic motion with an amplitude of 4 cm. At what displacement from the equilibrium position, is its energy half potential and kinetic ?
A glass slab is placed in the path of convergent light. The point of convergence of light
A cylindrical solid of mass M has radius R and length L. Its moment of inertia about a generator is
A constant torque of 1000 N-m turns a wheel of moment of inertia 200 kg-m2 about an axis through its centre. Angular velocity of the wheel after 3 s will be
At room temperature, a p-type semiconductor has
Electrical conductivity of a semiconductor
When a Van der Waals' gas undergoes free expansion then its temperature
A mountain climber finds that water boils at 80ºC. The temperature of this boiling water on Fahrenheit scale is
Curie is a unit of
In Young's double slit experiment, an interference pattern is obtained on a screen by a light of wavelength 6000 Å coming from the coherent sources S1 and S2. At certain point P on the screen third dark fringe is formed. Then the path difference S1p − S2p in microns is
A particle is projected at an angle of 45º with the horizontal. The kinetic energy of the particle, at the highest point in its flight, is (where K is initial kinetic energy of the particle)
If represent the sides AB and BC of a regular hexagon ABCDEF, then the vector equals
A body starts from rest travels a distance x in first two seconds and a distance y in next two seconds. The relation between x and y is
Two identical pn junctions may be connected in series with a battery in three ways as shown : The potential drops across the two pn junctions are equal in
Shown in the figure below is a meter-bridge set up with null deflection in the gravanometer.
The value of the unknown resistor R is
A student performs an experiment to determine the Young’s modulus of a wire, exactly 2 m long, by Searle’s method. In a particular reading, the student measures the extension in the length of the wire to be 0.8 mm with an uncertainty of 0.05 mm at a load of exactly 1.0 kg. The student also measures the diameter of the wire to be 0.4 mm with an uncertainty of 0.01 mm. Take g = 9.8 m/s2 (exact). The Young’s modulus obtained from the reading is
In the figure, the pulley P moves to the right with a constant speed u. The downward speed of A is vA, and the speed of B to the right is vB. Then
Which of the following will have an output of 1?
Two particles, each of mass m and charge q, are attached to the two ends of a light rigid rod of length 2R. The rod is rotated at constant angular speed about a perpendicular axis passing through its centre. The ratio of the magnitudes of the magnetic moment of the system and its angular momentum about the centre of the rod is
A wire loop ABCDEA carrying a current l is placed in X-Y plane as shown. The external magnetic field is applied in the region. Then
A transverse sinusoidal wave of amplitude a, wavelength λ and frequency f is travelling on a stretched string. The maximum speed of any point on the string is v/10, where v is the speed of propagation of the wave. If a = 10-3 m and v = 10 ms-1, then λ and f are given by
An object is dropped from rest. Its velocity versus displacement graph is