The resistance if a circular coil of 50 turns and 10 cm diameter is 5Ω. What must be the potential difference across that ends of the coil so as to nullify the earth’s magnetic field (H=0.314 gauss) at the centre of the coil? How should the coil be placed to achieve this result?
1. 0.5 V with plane of coil normal to the magnetic meridian
2. 0.5 V with plane of coil in the magnetic meridian
3. 0.25 V with plane of coil normal to the magnetic meridian
4. 0.25 V with plane of coil in the magnetic meridian
The resistance if a circular coil of 50 turns and 10 cm diameter is 5Ω. What must be the potential difference across that ends of the coil so as to nullify the earth’s magnetic field (H=0.314 gauss) at the centre of the coil? How should the coil be placed to achieve this result?
1. 0.5 V with plane of coil normal to the magnetic meridian
2. 0.5 V with plane of coil in the magnetic meridian
3. 0.25 V with plane of coil normal to the magnetic meridian
4. 0.25 V with plane of coil in the magnetic meridian
Subtopic: Earth's Magnetism (OLD NCERT) |
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If C and L denote the capacitance and inductance respectively, the units of LC are
Subtopic: Dimensions |
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The Kα line from Molybdenum (atomic number = 42) has a wavelength of 0.7078Å. The wavelength of Kαline of zinc (atomic number = 30) will be
Subtopic: Spectral Series |
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A body of mass 0.5 kg is projected under gravity with a speed of 98 m/s at an angle of 60 ° with the horizontal. The change in momentum (in magnitude) of the body is
1. 24.5 N-s
2. 49.0 N-s
3. 98.0 N-s
4. 50.0 N-s
2. 49.0 N-s
3. 98.0 N-s
4. 50.0 N-s
Subtopic: Projectile Motion |
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The dispersive powers of glasses of lenses used in an achromatic pair are in the ratio 5 : 3. If the focal length of the concave lens is 15 cm, then the nature and focal length of the other lend would be
1. convex, 9 cm
2. concave, 9 cm
3. convex, 25 cm
4. concave, 25 cm
2. concave, 9 cm
3. convex, 25 cm
4. concave, 25 cm
Subtopic: Lenses |
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A charge Q is divided into two parts of q and Q-q. If the coulomb repulsion between them when they are separated is to be maximum, the ratio of 
should be
should be1. 2
2. 1/2
3. 4
4. 1/4
2. 1/2
3. 4
4. 1/4
Subtopic: Coulomb's Law |
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A rectangle vessel when full of water, takes 10 mint to be emptied through an orifice in its bottom. How much time will it take to be emptied when half filled with water?
1. 9 min
2. 7 min
3. 5 min
4. 3 min
2. 7 min
3. 5 min
4. 3 min
Subtopic: Bernoulli's Theorem |
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If there were no gravity, which of the following will not be there for a fluid?
1. Viscosity
2. Surface tension
3. Pressure
4. Archimedes’ upward thrust
2. Surface tension
3. Pressure
4. Archimedes’ upward thrust
Subtopic: Archimedes' Principle |
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