Jamb Physics 2000 Past Questions and Answers

Question 31:

• JAMB 2000

If the fraction of the atoms of a radioactive material left after 120years is 1/64, what is the half-life of the material?

A. 24 years
B. 20 years
C. 10 years
D. 2 years

Question 32:

• JAMB 2000

A certain radioactive source emits radiations that were found to be deflected by both magnetic and electric fields. The radiations are

A. Beta rays
B. Gamma rays
C. X-rays
D. Unltr-violet rays

Question 33:

• JAMB 2000

A 2H inductor has negligible resistance and is connected to a 50/Ï€ Hz A.C. Supply. The reactance of the inductor is

A. 200 Ω
B. 50 Ω
C. 100/π Ω
D. 25/π Ω

Question 34:

• JAMB 2000

A cell of internal resistance 1Ω supplies current to an external resistor of 3Ω. The efficiency of the cell is

A. 25%
B. 33%
C. 50%
D. 75%

Question 35:

• JAMB 2000

A conductor of length 2m carries a current of 0.8A while kept in a magnetic field of magnetic flux density 0.5T. The maximum force acting on it is

A. 0.2N
B. 0.8N
C. 3.2N
D. 8.0N