Question 4436:

• NECO 2002

A transformer supplies 12V when connected to a 240V mains. If the transformer takes 0.120A from the mains when used to light a 12V, 24W lamp, what is its efficiency?

A. 57.20%
B. 66.60%
C. 83.30%
D. 92.50%
E. 100%

Question 4437:

• NECO 2002

Which of the following is/are TRUE of nuclear fission?

I. A heavy nucleus is split into two nuclei of comparable masses.
II. Two light nuclei are joined together to form a heavier nucleus.
III. The total mass of the products is less than that of the reactants.

A. I only
B. II only
C. III only
D. I and III only
E. II and III only

Question 4438:

• NECO 2002

A converging lens of focal length 5cm forms a virtual image which is 20cm from the lens. How far from the lens is the object?

A. 2.0cm
B. 4.0 cm
C. 6.7cm
D. 20.0cm
E. 25.0cm

Question 4439:

• NECO 2002

In an operating X-ray tube, a high p.d is applied between the cathode and the anode for the purpose of ____________

A. Accelerating the electrons to a very high energy
B. Concentrating electrons on the target
C. Heating the anode
D. Heating the cathode
E. Producing a stream of electrons

Question 4440:

• NECO 2002

The ability of the eye to focus on objects at various distances is known as ____________

A. Accommodation
B. Astigmatism
C. Eye ring
D. Myopia
E. Presbyopia