- AVelocity
- BMomentum
- CKinetic energy
- DAngular velocity
Explanation:
Since the force on the charge is always normal to the velocity of the charge so, field does not work on the particle and the magnitude of velocity remains same.
So, kinetic energy is same, whereas velocity changes direction. So, velocity, momentum and angular velocity changes.
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The photoelectric threshold wavelength of a certain metal is 3000Å. If the radiation of 2000Å is incident on the metal
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(a) Electrons will be emitted |
(b) Positrons will be emitted |
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(c) Protons will be emitted |
(d) Electrons will not be emitted |
Assertion : The specific charge for positive rays is a characteristic constant.
Reason : The specific charge depends on charge and mass of positive ions present in positive rays.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
A highly conducting ring of radius R is perpendicular to and concentric with the axis of a long solenoid as shown in fig. The ring has a narrow gap of width d in its circumference. The solenoid has cross sectional area A and a uniform internal field of magnitude B0. Now beginning at t = 0, the solenoid current is steadily increased to so that the field magnitude at any time t is given by B(t) = B0 + at where α > 0. Assuming that no charge can flow across the gap, the end of ring which has excess of positive charge and the magnitude of induced e.m.f. in the ring are respectively

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(a) X, A𝛼 |
(b) X, pR2𝛼 |
(c) Y, 𝜋A2𝛼 |
(d) Y, pR2𝛼 |
A beam of well collimated cathode rays travelling with a speed of 5
enter a region of mutually perpendicular electric and magnetic fields and emerge undeviated from this region. If |B| = 0.02T, the magnitude of the electric field is
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(a) |
(b) 2.5 |
(c) 1.25 |
(d) 2 |
Equivalent resistance between A and B will be
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(a) 2 ohm |
(b) 18 ohm |
(c) 6 ohm |
(d) 3.6 ohm |
On increasing the plate separation of a charged condenser, the energy
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(a) Increases |
(b) Decreases |
(c) Remains unchanged |
(d) Becomes zero |
Light of wavelength
strikes a photo-sensitive surface and electrons are ejected with kinetic energy E. If the kinetic energy is to be increased to 2E, the wavelength must be changed to
where
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(a) |
(b) |
(c) |
(d) |