Question 646:

• JAMB 1991

When the bottom tip of a vibrating tuning fork is held in contact with a wooden box, a louder sound is heard. This phenomenon is known as

A. Beats
B. Echoing
C. Resonance
D. Reverberation

Question 647:

• JAMB 1991

Which of the following statements is CORRECT about the earth's magnetic field?

A. The angle of dip is the angle which a freely suspended magnet makes with the vertical
B. The angle of declination is the angle between the magnetic meridian and the geographic meridian
C. The angle of declination is the angle which a magnetic compass makes with the magnetic meridian
D. The angle of inclination is the difference between the angle of dip and the angle of declination

Question 648:

• JAMB 1991

An insulated rod when rubbed with a material acquires

A. A negative charge if it is made of glass and rubbed with silk
B. No charge if it is made of glass and rubbed with fur
C. No charge if it is made of copper and rubbed with silk
D. A positive charge if it is made of copper and rubbed with fur

Question 649:

• JAMB 1991

The function of the system of granulated carbon mixed with manganese (IV) oxide in a Letanche cell is to

A. Increase the e.m.f. of the cell to 2.0V
B. Prevent local action in the cell
C. Prevent polarisation in the cell
D. Make the cell black and hence a good radiator

Question 650:

• JAMB 1991

A moving coil galvanometer of 300\(\Omega\) resistance gives full scale deflection for 1.0mA. The resistance R, of the shunt that is required to convert the galvanometer into a 3.0A ammeter is

A. 899.70\(\Omega\)
B. 10.00\(\Omega\)
C. 0.10\(\Omega\)
D. 0.01\(\Omega\)