31. Which of the following is correct about an electric cell?
- A. Primary cell produces a large current for a long time
- B. Secondary cell has a very high internal resistance
- C. Primary cell has a very low internal resistance
- D. Secondary cell has a very low internal resistance
Correct Option: Answer is D
About electric cell
Primary cells are used up gradually often the cells are use and it can’t be recharged
Secondary cells or accumulated can be recharged and used for a long period of time and their main advantage is that they have low internal resistance
32. Which of the following is a semiconductor
- A. copper
- B. silicon
- C. plastic
- D. Iron
Correct Option: Answer is B
Semi-conductor have an electric conductivity intermediate in value between that of a pure metal and a good insulator. Silicon is an example
33. Which of the following surfaces will absorbs radiant heat energy heat?
- A. white
- B. red
- C. black
- D. blue
Correct Option: Answer is C
A black solution is a better radiator of heat and allow a better absorber of heat.
34. It is known that a neutron exists in a light atomic nucleus
Which of the following also exists in the nucleus?
- A. An electron
- B. A β – particle
- C. β – particle
- D. proton
Correct Option: Answer is D
Nucleus of atom is made up of neutron and proton
35. The instrument to measure the relative density of liquid is
- A. thermometer
- B. hydrometer
- C. spring balance
- D. beaker
Correct Option: Answer is B
Thermometer is used to measure temperature
Hydrometer is used to measure relative density of liquid.
Spring balance is used to measure the weight of an object
Beaker is used to measure or take volume of a liquid
36. What is the speed of a body vibrating at 50 cyclic per second
- A. 100 πrads−1
- B. 200 πrads−1
- C. 50 πrads−1
- D. 400 πrads−1
Correct Option: Answer is A
∴ 50 cycle = 2 π rad × 50 = 100 πrad
∴ = angular speed = 50 cycles per seconds = 100 π rads−1
37. The action of blotting paper on ink is due to
- A. diffusion
- B. osmosis
- C. capillarity
- D. surface tension
Correct Option: Answer is C
Capillarity is the tendency of a liquid to rise or fall in a narrow tube and it explains why a blotting paper absorbs ink
38. When two mirrors are placed at an angle of 900 to each other, how many images will be formed when an object is placed in front of the mirrors
- A. 5
- B. 4
- C. 3
- D. 2
Correct Option: Answer is C
When two mirror are inclined at an angle θ, the number of images formed, n = \(\frac{360}{\theta}\) − 1
∴ since \(\theta\) = 90o
∴ \(\frac{360}{\theta}\) − 1
= 4 − 1
= 3
39. If silicon is doped with phosphorus, what type of semiconductor material will be formed?
- A. Zener material
- B. P-n junction
- C. n-type
- D. p-type
Correct Option: Answer is B
When silicon is doped with a trivalent atom. A p-type semi-conductor will be formed when silicon is doped with a pentavalent atom such as arsenic, a n-type semi-conductor will be formed
Phosphorous is a pentavalent element, so it will produce a o -type semi-conductor
40. Calculate the angle of minimum deviation of a 60o prism of a refractive index [sin-10.75 = 49o]
- A. 38.00o
- B. 19.47o
- C. 16.25o
- D. 49o
Correct Option: Answer is A
For a refractive index () = \(\frac{\sin\frac{1}{2} (A + D)}{\sin\frac{1}{2}A}\)
D = angle of minimum deviation
A = refractive angle of the prism
1.5 = \(\frac{\sin\frac{1}{2} (60 + D)}{\sin\frac{1}{2} \times 60}\)
1.5 = \(\frac{\sin\frac{1}{2} (60 + D)}{\sin 30}\)
Sin \(\frac{1}{2}\) (60 + D) = 1.5 * Sin 30
Sin \(\frac{1}{2}\) (60 + D) = 0.75
\(\frac{1}{2}\) (60 + D) = Sin-1 (0.75)
but Sin-1 (0.75) = 49o
\(\frac{1}{2}\) (60 + D) = 49
60 + D = 2 * 49 = 98o
D = 98o – 60o
D = 38o