The number of holes in an intrinsic semiconductor

• A. is not equal to the number of free electrons
• B. is greater than the number of free electrons
• C. is equal to the number of free electrons
• D. is less than the number of free electrons

A cell of internal resistance 2 π supplies current to a 6 π resistor. The efficiency of the cell is

• A. 12.0%
• B. 25.0%
• C. 33.3%
• D. 75.0%

If the efficiency of a transformer is 100%, which of the following equations would be correct?

• A. N\(_p\)E\(_p\) = N\(_s\)E\(_s\)
• B. N\(_s\)I\(_p\)= N\(_p\)I\(_s\)
• C. N\(_s\)I\(_s\) = N\(_p\)I\(_p\)
• D. I\(_p\)E\(_s\) = I\(_s\)E\(_p\)

A body of volume 0.046m³ is immersed in a liquid of density 980kgm^-3 with \(\frac{3}{4}\) of its volume submerged. Calculate the upthrust on the body. [g = 10ms^-2]

• A. 11.27N
• B. 33.81N
• C. 112.70N
• D. 338.10N

A bat emits a sound wave at a speed of 1650.0ms^-1 and receives the echoes 0.15s later. Calculate the distance of the bat from the reflector

• A. 8.75m
• B. 16.50m
• C. 87.75m
• D. 123.75m

The pressure P, volume V, and absolute temperature T of a given mass of an ideal gas change simultaneously. Which of the followng equations is correct about the gas?

• A. PV = \(\frac{constant}{T}\)
• B. \(\frac{P}{T} = Constant\)
• C. \(\frac{P}{V} = \frac{constant}{T}\)
• D. \(\frac{I}{T} = \frac{constant}{PV}\)

If the linear magnification of the objective and eyepiece convex lenses of a compound microscope are 4 and 7 respectively. Calculate the angular magnification of the microscope

• A. 2
• B. 3
• C. 11
• D. 28

If it takes 5.0 hrs to drain a container of 540.0cm³ of water, what is the flow rate of water from the container in kg^-1? [Density of water = 1000kgm^-3]

• A. 32.5kg^-1 s
• B. 31.5kg^-1
• C. 30.8kg^-1 s
• D. 30.0kg^-1 s

Which of the following types of types of motion will be produced when a pair of equal and opposite non-collinear parallel forces acts on a body?

• A. vibrational motion
• B. random motion
• C. translational motion
• D. rotational motion

The major difference between a pure semiconductor and a pure metal is that

• A. metals are harder than semiconductor
• B. while resistance of metals decrease with temperature , the reverse is the case for semiconductor
• C. the resistance of metals increases with temperature, while for semiconductors, it is the reverse
• D. metals have forbidden gaps while semiconductors have not