1. The peak value of A.C is 20 A, what will the RMS value?
(a) 20 A
(b) 20 / √2 A
(c) 20√2 A
(d) zero
Ans. (b) 20 / √2 A
2. What is the phase difference between e.m.f. and current in resistive A.C. circuit?
(a) 90°
(b) 0°
(c) 45°
(d) 60°
Ans. (a) 90°
3. Which of the following electromagnetic wave has longest wavelength?
(a) Red light
(b) Blue light
(c) Green light
(d) X-rays
Ans. (a) Red light
4. What will be the power of a lens of focal length 0.25 m?
(a) 0.25 D
(b) 1 D
(c) 4 D
(d) 25 D
Ans. (c) 4 D
5. The radii of curvature of the faces of a double convex lens are 10cm and 15cm. Its focal length is 12cm. What is the refractive index of glass?
(a) 1.4
(b) 1.5
(c) 1.6
(d) 1.2
Ans. (b) 1.5
6. The brilliancy of diamond is due to which of the following?
(a) Interference
(b) Total Internal Reflection
(c) Refraction
(d) Reflection
Ans. (b) Total Internal Reflection
7. What will be the frequency of an electromagnetic wave of wavelength 300 micrometer?
(a) 1014 Hz
(b) 1012 Hz
(c) 3 × 1012 Hz
(d) 1011 Hz
Ans. 1012 Hz
8. What is the ionization energy of H-atom?
(a) 13.6 eV
(b) 1 eV
(c) 1 J
(d) none of these.
Ans. (a) 13.6 eV
9. Which of the following materials may be doped in Si to make N type semi-conductor?
(a) Cu
(b) Fe
(c) Arsenic (As)
(d) Al
Ans. (c) Arsenic (As)
10. Which of the following is a semi-conductor?
(a) U
(b) Ge
(c) Bi
(d) Fe
Ans. (b) Ge
11. Which of the following is not a series of H-atom?
(a) Balmer
(b) Raman
(c) Pfund
(d) Paschen
Ans. (b) Raman
12. When frequency of incident photon is decreased, then what happens to stopping potential?
(a) Increase
(b) Decrease
(c) Remains same
(d) None of these.
Ans. (b) Decrease
13. When speed of a moving particle increase, then its de-Broglie wavelength will?
(a) increase
(b) remains same
(c) decrease
(d) None of these.
Ans. (c) decrease
14. What is the SI unit of resistivity?
(a) Ohm
(b) Ohm-cm
(c) Ohm-m
(d) Volt
Ans. (c) Ohm-m
15. When three capacitors of 2 µF each are connected in parallel, then net capacitance will be :
(a) 6 µF
(b) 2 µF
(c) 0.5 µF
(d) 1 µF
Ans. (a) 6 µF
16. The charge of a Proton is :
(a) 1.6 C
(b) 1 C
(c) + 1.6×10-19 C
(d) – 1.6×10-19 C
Ans. (c) + 1.6×10-19 C
17. For a conductor of length (l) and area of cross-section (A), the relation between its resistance (R) and its resistivity is:
(a)
(b)
(c)
(d) None of these.
Ans. (b)
18. In which of the following the resistance decreases with increase in temperature?
(a) Cu
(b) Fe
(c) Al
(d) Ge
Ans. (d) Ge
19. The force acting on a charge moving parallel to magnetic field is :
(a) qvB
(b) q2vB
(c) q / (vB)
(d) Zero
Ans. (d) Zero
20. The magnetic field at the centre of a circular coil of radius r, carrying current I is given by :
(a)
(b)
(c)
(d) None of these.
Ans. (d) None of these.
21. What is the value of angle of dip at poles?
Ans. Angle of dip at poles (δ) is 90º, on equation δ = 0º
22. Write Lorentz force equation.
Ans. Lorentz Force equation F= q(E+V x B )
23. What is the frequency of domestic A.C. supply in India?
Ans. 50Hz
24. Define resistance of a material.
Ans. Resistance of a material is the obstructions posed by that material to the flow of electric current through it.
R= V/I
25. What is the SI unit of permeability ?
Ans. Henry per Metre
26. Define Self-Inductance.
Ans. Self Inductance is the property of a coil by virtue of which the coil opposes any change in the strength of current flowing through it by inducing an emf in itself.
27. Which has large band gap out of semi- conductor and insulator?
Ans. Insulator has large band gap as compared to semi-conductor.
28. Define isobars of an element.
Ans. Those elements which having same mass number but different atomic numbers. Example- Ar and Ca has same mass number of 40 but having different atomic Number of 18 and 20.
29. Which semi-conductor device can be used to make half-wave rectifiers?
Ans. p-n junction diode is used to make half-wave rectifiers.
30. Give one example of isotope.
Ans. Isotope of Hydrogen
11H – Protium, 21H – Deuterium, 31H – Tritium
31. For photo-electric emission, write Einstein’s equation.
Ans. Einstein’s Equation for Photo-electric emission –
1/2 MV2 max = hv-∅0 = hv-hv0 = h(v-v0), Where h is Plank’s constant, v0 is threshold frequency, v is frequency of light radiation.
32. Write formula for magnification of compound microscope.
Ans. Magnification of compound microscope (m) is
m = me × mo = ( 1 – vo/fo )( 1 + d/fe )
Where me is the magnification by eye lens and mo mag
33. Define magnification of a lens and give its formula.
Ans. Magnification produced by a lens is defined as the ratio of the size of the image to the size of object. Magnification is represented by m.
m = size of image / size of object
34. When two thin lenses of focal lengths f1 and f2 are placed in contact with each other. Then focal length of combination will be fe is … .
Ans. 1/fe = 1/f1 + 1/ f2
35. Calculate the refractive index of a medium if critical angle is 30° .
Ans. Refractive index (µ) = 1 / SinC, Where C is critical angle.
C = 30°
So, µ = 1 / Sin30° = 1 / (1/2)
µ = 2