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JEE Main Physics Questions

Q1.The termistors are usually made of
(a) metal oxides with high temperature coefficient of resistivity
(b) metals with high temperature coefficient of resistivity
(c) metals with low temperature coefficient of resistivity
(d) semiconducting materials having low temperature coefficient of resistivity

Q2. The thermo e.m.f. of a thermo -couple is 25 Μv/o C at room temperature. A galvanometer of 40 ohm resistance, capable of detecting current as low as 10–5 A, is connected with the thermo couple. The smallest temperature difference that can be detected by this system is
(a) 16o C
(b) 12 o C
(c) 8 o C
(d) 20 o C

Q3. The thermo emf of a thermocouple varies with the temperature θ of the hot junction as E = aθ + bθ in volts where the ratio a/b is 700°C. If the cold junction is kept at 0°C, then the neutral temperature is
(a) 1400°C
(b) 350°C
(c) 700°C
(d) No neutral temperature is possible for this termocouple.

Q4. The threshold frequency for a metallic surface corresponds to an energy of 6.2 eV and the stopping potential for a radiation incident on this surface is 5 V. The incident radiation lies in
(a) ultra-violet region
(b) infra-red region
(c) visible region
(d) X-ray region

Q5. The time period of a satellite of earth is 5 hours. If the separation between the earth and the satellite is increased to 4 times the previous value, the new time period will become
(a) 10 hours
(b) 80 hours
(c) 40 hours
(d) 20 hours

Q6. The time period of an earth satellite in circular orbit is independent of
(a) both the mass and radius of the orbit
(b) radius of its orbit
(c) the mass of the satellite
(d) neither the mass of the satellite nor the radius of its orbit.

Q7. The total energy of a particle, executing simple harmonic motion is
(a) independent of x
(b) x2

Q8. The transition from the state n = 4 to n = 3 in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from:
(a) 3 2
(b) 4
(c) 5
(d) 2

Q9. The velocity of a particle is v = v0 + gt + ft2. If its position is x = 0 at t = 0, then its displacement after unit time (t = 1) is  
(a) v0 + g/2 + f
(b) v0 + 2g + 3f
(c) v0 + g/2 + f/3
(d) v0 + g + f

Q10. The work function of a substance is 4.0 eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately.
(a) 310 nm
(b) 400 nm
(c) 540 nm
(d) 220 nm

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