If the refractive index of a medium in air is 2.0, what is the critical angle for this medium?

• A. 30^o
• B. 42^o
• C. 45^o
• D. 50^o

In the diagram below, a rod 50 cm long of uniform cross-section is suspended horizontally on a fulcrum, F, by the action of two forces. What is the weight of the

• A) 40N
• B) 80N
• C) 120N
• D) 200N

Which of the following has the lowest internal resistance when new?

• A. leclanche cell
• B. Daniel cell
• C. Accumulator
• D. Torch battery

Which of the following statements about magnetic lines of force is not correct?

• A. a magnnetic line of force is an imaginary line which the north pole of a magnet would describe if it is free to moves
• B. magnetic lines of force do not cross one another
• C. magnetic lines of force are closely packed together at neutral point
• D. the presence of magnetic lines of force in a region indicates the presence of a magnetic field

The difference between X-rays and gamma rays is that

• A. x-rays are more penetrating than gamma rays
• B. x-rays are electromagnetic radiations while gamma rays are negatively charged radiation
• C. x-rays have higher frequencies than gamma rays
• D. x-rays arise from energy changes in the electronic structure of atoms while gamma rays come from the nucleus

The frequency of the wave in the diagram below is

• A) 0.17 Hz
• B) 0.25 Hz
• C) 1.57 Hz
• D) 1.05 Hz

Which of the following physical processes cannot be explained by the molecular theory of matter?

• A. evaporation
• B. thermal conduction
• C. radiation of heat
• D. convectional current of fliuds

A real image three times the size of an object is formed 24cm from a converging mirror. what is the focal length of the mirror.

• A. 16cm
• B. 6cm
• C. 8cm
• D. 12cm

Which of the following is not a consequence of hydrogen bubbles covering the copper plate of a primary cell?

• A. formation of hydrogen bubbles electrode
• B. increase in the resistance of the cell
• C. local action
• D. polarization

Steel bars each of length 3m at 28°C are to be used for constructing a rail line. If the linear expansitivity of the steel is 1 x \(10^{-5}K^{-1}\),what is the safety gap that must be left between the successive bars if the highest temperature expected is 40°C?

• A. 1.2x \(10^{-1}cm\)
• B. 7.2x\(10^{-1}cm\)
• C. 6x\(10^{-1}cm\)
• D. 3.6x\(10^{-2}cm\)