Question 4271:

• WAEC 2020

The vacuum between the double walls of a thermos flask reduces heat loss through

A. Conduction and radiation
B. Convection and conduction
C. Radiation only
D. Conduction only

Question 4272:

• WAEC 2020

In photoelectric effect, the number of electrode emitted per second from a metallic surface is proportional to the

A. Intensity of the incident radiation
B. Frequency of the incident radiation
C. Energy of the incident radiation
D. Work function of the metal.

Question 4273:

• WAEC 2020

When two cells of negligible internal resistances and equal e.m.f. denoted by E\(_1\) and E\(_2\) are connected in parallel, combined e.m.f. E is given by

A. E = E\(_1\) + E\(_2\)E = \(\frac{E_1}{E_2}\)
B. \(\frac{1}{E} = \frac{1}{E_1} + \frac{1}{E_2}\)
C. E = E\(_1\) = E\(_2\)

Question 4274:

• WAEC 2020

Which of the following statement about viscosity is not true? it

A. Depends on areas of the surfaces in contact
B. Occurs in fluids
C. Is independent of the relative velocity of the layers
D. Depends on the tangential force between the layers

Question 4275:

• WAEC 2020

In a solar panel for heat supply, state the function of each of the following parts: (a) metal flat plate; (b) thermal insulator: (c) tubes.