Question 4306:

• WAEC 2021

Which of the arrangements of radiations below shows decreasing order of wavelengths?

A. X-rays> radio waves > infrared radiations
B. Radio waves> infrared radiations > X-rays
C. Infrared radiations > radio waves > X-rays
D. X-rays> infrared radiations > radio waves

Question 4307:

• WAEC 2021

An electric pressing iron is connected to the mains using an insulated wire. wire becomes very hot.
The heat generated in the wire can be minimized by replacing the wire with one of?

A. Thinner insulation.
B. Greater diameter.
C. Smaller diameter.
D. Thicker insulation.

Question 4308:

• WAEC 2021

In the diagram above, a bulb is lit by drawing 2.0A from 440V a.c. source. Calculate the cost of keeping the bulb on for two days at $0.40 per kilowatt-hour .

A. $16.90
B. $84.48
C. $1690.00
D. $8.48

Question 4309:

• WAEC 2021

Which of the following actions will increase capacitance of a parallel plate capacitor?
I. Decreasing the distance between the plates
II. Increasing the distance between the plates.
III. Increasing the area of the plates overlap.
IV. Avoiding the use of dielectric between the plate

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

Question 4310:

• WAEC 2021

A metallic sphere is heated from 27°C to 200°C Without change of state. Which of the following changes would have resulted from the heating?

A. No changes occur in its volume and density
B. Its volume increases and its density increases
C. Its volume increases and its density decrease
D. Its volume increases without a change in density