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# NDA Science Practice Test

Q1.
The sun is visible a little before the actual sunrise because of which one of the following?
(a) Atmospheric reflection
(b) Atmospheric dispersion
(c) Atmospheric diffraction
(d) Atmospheric refraction

Q2. Light travels in optical fibre irrespective of its shape because it is a device by which signals can be transferred from one location to another. It is based on the phenomenon of
(a) diffraction of light
(b) refraction of light
(c) polarisation of light
(d) total internal reflection of light

Q3. Two thin convex lenses of focal lengths 4 cm and 8 cm are separated by a distance of 4 cm in air. The combination will have the focal length
(a) 4 cm
(b) 8 cm
(c) 12 cm
(d) 32 cm

Q4. The effective resistance of two wires is 2 x. The resistance of one wire is two times that of the other wire and is three times the effective resistance. Which one of the following is correct in respect of value of x?
(a) x can take only one value.
(b) x must only be greater than or equal to 1
(c) x can take any positive real value
(d) The information given above is inconsistent

Q5. A wire of resistance 16 W is bent in the form of a circle. What is the effective resistance between diametrically opposite points?
(a) 1 W
(b) 2 W
(c) 4 W
(d) 8 W

Q6. Consider the following: Heat produced in a conductor carrying current is independent of
1. Current passing through it.
2. Thermal conductivity.
3. Specific resistance.
Which of the statement given above is/are correct?
(a) 1 and 3
(b) 2 only
(c) 1 and 2
(d) 2 and 3

Q7. The specific resistance of a conducting wire depends upon
(a) length of the wire, area of cross-section of the wire and material of the wire
(b) length of the wire and area of cross-section of the wire but not on the material of the wire
(c) material of the wire only but neither on the length of the wire nor on the area of cross-section of the wire
(d) length of the wire only but neither on the area of cross-section of the wire nor on the material of the wire

Q8. Two copper wires A and B of length l and 2l respectively, have the same area of cross- section. The ratio of the resistivity of wire A to the resistivity of wire B is
(a) 4
(b) 2
(c) 1
(d) 1/2

Q9. The earth’s magnetic field is approximately
(a) 1 Tesla
(b) 2 Gauss
(c) 104 Tesla
(d) 1 Gauss

Q10.  3. Which one of the following is the correct sequence of the wavelengths of radiations?
(a) UV > Green> IR > Hard X-rays
(b) IR > Green> UV > Hard X-rays
(c) UV > Hard X-rays> IR > Green
(d) IR > Hard X-rays> Green> UV

Q11. Propagation of light quanta may be described by
(a) Photons
(b) Protons
(c) Neutrons
(d) Electrons

Q12. An oxide of nitrogen has molecular weight.30. What is the number of electrons in one molecule of the compound?
(a) 14
(b) 15
(c) 22
(d) 23

1. (d)2. (d)3. (a)4. (c)5. (c)6. 7. (c)8. (b)9. (d)10. b11. (a)12. c

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