Question 4206:

• WAEC 2019

Which of the following statements is the correct reason for using soft iron in making the armature or an electric bell?

A. It is a diamagnetic material
B. It loses its magnetism readily
C. It is not easily magnetized
D. It retains its magnetism for a long time

Question 4207:

• WAEC 2019

The diagram above illustrates a meter bridge circuit under balanced condition. Determine the value of x.

A. 71.4 cm
B. 10.0 cm
C. 28.6 cm
D. 57.2 cm

Question 4208:

• WAEC 2019

Which of the following devices is used for storing electric charges?

A. Transformer
B. Ammeter
C. Potentiometer
D. Capacitor

Question 4209:

• WAEC 2019

An electron of mass 9.1 x 10\(^{-31}\) kg moves with a speed of 2.0 x 10\(^6\) ms\(^{-1}\) round the nucleus of an atom in a Circular path of radius 6.1 x 10(^{11}\) m. Determine the angular speed of the electron.

A. 3.28 x 10\(^{16}\) rad s\(^{-1}\)
B. 8.55 x 10\(^{3}\) rad s\(^{-1}\)
C. 9.11 x 10\(^{13}\) rad s\(^{-1}\)
D. 5.22 x 10\(^{15}\) rad s\(^{-1}\)

Question 4210:

• WAEC 2019

An electron of mass 9.1 x 10\(^{-31}\) kg moves with a speed of 2.0 x 10\(^6\) ms\(^{-1}\) round the nucleus of an atom in a Circular path of radius
6.1 x 10\(^{11}\) m. Calculate the centripetal force acting on the electron.

A. 7.7 x 10\(^{47}\) N
B. 6.0 x 10\(^{-8}\)N
C. 3.0 x 10\(^{-14}\)N
D. 1.3 x 10\(^{-26}\)N