The work function for metals A,B abd C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein’s equation the metals which will emit photoelectrons for a radiation of wavelength 4100 Å is/are […]
When a wire of uniform cross-section a, length l and resistance R is bent into a complete circle, resistance between any two of diametrically opposite points will be
Options
(a) R/4 (b) 4R […]
Fission of nuclei is possible because the binding energy per nucleon in them
Options
(a) increases with mass number at low mass numbers (b) decreases with mass number at low mass numbers (c) […]
In the reaction ₁²H+₁³H+₂⁴He+₀¹n, if the binding energies of ₁²H,₁³H and ₂⁴He are respectively a,b and c (in MeV), then the energy (in MeV) released in this reaction is
Options
(a) a+b+c (b) […]
A point source emits sound equally in all directions in a non-absorbing medium. Two points P and Q are at distances of 2 m and 3 m respectively from the source. The ratio of the […]
Application of a forward bias to a P-N junction
Options
(a) Widens the depletion region (b) Increases the potential difference across the depletion zone (c) Increases the number of doners on the N […]
The circular motion of a particle with constant speed is
Options
(a) Periodic but not simple harmonic (b) Simple harmonic but not periodic (c) Period and simple harmonic (d) Neither periodic not simple harmonic
Imagine a new planet having the same density as that of earth but it is 3 times bigger than the earth in size. If the acceleration due to gravity on the surface of earth is […]
A photosensitive metallic surface has work function, hν₀. If photons of energy 2hν₀ fall on this surface, the electrons come out with a maximum velocity of 4×10⁶m/s. When the photon energy is increased to 5hν₀, […]
For a satellite moving in an orbit around the earth, the ratio of kinetic energy to potential energy is
Options
(a) (1/2) (b) 1/√2 (c) 2 (d) √2
Correct Answer:
(1/2)
Explanation:
-GMm/R² […]
2017 Copyright Doctor Dreams Training Academy