3) colour of evening sky.
4) operation of optical fibers.
Which of the statements given above are correct? [NDA 2008]
(a) 1 and 4
(b) 3 and 4
(c) 2 and 3
(d) 1 and 2
Ans : (a)
267. Which of the following statements is/are true regarding a light wave traveling from air to glass? [NDA 2008]
1) Its frequency remains unchanged.
2) Its speed changes.
(a) 1 only
(b) 2 only
(c) Both 1and 2
(d) Neither 1 nor 2
Ans : (c)
268. DC current can be controlled by which one of the following components? [NDA 2008]
(a) Impedance
(b) Resistance
(c) Capacitance
(d) Inductance
Ans : (b)
269. Consider the statements; The fraction of a ball floating inside the liquid depends upon
1) density of the liquid.
2) mass of the ball.
3) density of the ball.
Which of the statements given above are correct? [NDA 2008]
(a) 1 and 2
(b) 2 and 3
(c) 1 and 3
(d) 1, 2 and 3
Ans : (c)
270. Which one among the following radiations carries maximum energy? [NDA 2008]
(a) Ultraviolet rays
(b) Gamma-rays
(c) X-rays
(d) Infrared rays
Ans : (b)
271. The neutron, proton, electron and alpha particles are moving with equal kinetic energies. How can the particles be arranged in the
increasing order of their velocities? [NDA 2008]
(a) Alpha particle-neutron-proton- electron
(b) Proton-electron-neutron-alpha particle
(c) Electron-proton-neutron-alpha particle
(d) Neutron-proton-electron-alpha particle
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