Question 4686:

A magnet is moved through a coil of wire. The emf produced in the wire depends on ____________

A. The number of turns in the coil
B. The strength of the magnet
C. The speed at which the magnet is moved
D. All of the above
E. None of the above

Question 4687:

A potential difference of 6v is used to produce a current of 5A for 200s through a heating coil. The heat produced is ____________

A. 4800cal
B. 6000cal
C. 2400j
D. 240kcal
E. 600j

Question 4688:

Two boys are communicating with each other by stretching a string passing through a hole punched in the bottom of each of the two tin cans. The physical principle employed is that sound travels

A. Mainly through air
B. Fainter in stretched string
C. Faster through gasses than in solids and liquids
D. With greater ease through a string than in air
E. None of the above is correct

Question 4689:

The hatch door of a submarine has an area of 0.5 m². The specific gravity of seawater is 1.03. Assume that g = 10m/s²and neglect the atmospheric pressure. The force exerted by the sea water on the hatch door at a depth of 200m is ____________

A. \(1.03 x 10^5N\)
B. 1.03 x 10⁴ Nm²
C. 2.6 x 10³Nm²
D. \(2.06 x10_11 N\)
E. 1.03 x 103 N.

Question 4690:

When equal weights of iron and water are subjected loan equal supply of heat, it is found that the piece of iron becomes much hotter than water after a short time because ____________

A. The specific heat or iron is higher than water
B. Iron is in solid form
C. Water is in liquid form
D. The specific heat of water is higher than that of iron
E. The specific heat of iron is infinite