Question 136:

• JAMB 1980

The best material for the core of the primary and secondary coils of an induction coil is

A. Copper, because it has a good conductor of electricity
B. Steel, because it becomes magnetic and retains its magnetism for a long time
C. Rubber, because it is a good insulator and the user is prevented from shock
D. Soft iron, because it becomes magnetic but easily loses its magnetism
E. Glass, because it is transparent

Question 137:

• JAMB 1980

Which of the following radiations cannot be deflected by a magnetic field?

A. \(\alpha\)
B. \(\beta\)
C. \(\gamma\)
D. \(\beta\) and \(\gamma\)
E. None of them

Question 138:

• JAMB 1980

Which of the following elements is the best absorber of X-rays?

A. Hydrogen
B. Oxygen
C. Calcium
D. Copper
E. Lead

Question 139:

• JAMB 1980

a calorimeter of thermal capacity 80j contains 20g of water at 25^oC. Water at 100^oC is added so that the final temperature of the set-ups is 50^oC. The amount of water added is (Heat capacity of water = 4.18J/g/^oC)

A. 20g
B. 25g
C. 45g
D. 50g
E. 100g

Question 140:

• JAMB 1980

the ratio of the linear expansivity of copper to that of iron is approximately 1.5. A specimen of iron and a specimen of copper expands by the same amount per unit rise in temperature. The ratio of their length is

A. 3
B. 1.5
C. 1.32
D. 1
E. 0.67