Waec Physics Past Questions
Question 1726
The speed of fast-moving neutrons in a nuclear reactor can be reduced by using?
- A. graphite rods
- B. concrete shield
- C. iron rods
- D. boron rods
Question 1727
.An inductor of inductance 10 H is connected across an a.c circuit source of 50 V, 100 Hz. What is the current in the circuit? [\(\pi\) = 3.14]
- A. 0.200A
- B. 0.070A
- C. 0.050A
- D. 0.008A
Question 1728
The half-life of a radioactive substance is 15 hours. If at some instance, the sample has a mass of 512 g, calculate the time it will take \(\frac{7}{8}\) of the sample to decay
- A. 15 hours
- B. 30 hours
- C. 45 hours
- D. 60 hours
Question 1729
Gamma rays are produced when?
- A. high velocity electrons are abruptly stopped in metals
- B. energy changes occur within the nuclei of atoms
- C. energy changes occur within the electronic structure of atoms
- D. electrons are deflected in very strong magnetic fields
Question 1730
If the kinetic energy of an electron is 100 eV, what is the wavelength of the de-Broglie wave associated with it? [h = 6.6 x 10\(^{-34}\) J s, e = 1.6 x 10\(^{19}\)C, m\(_{e}\), = 9.1 x 10\(^{-31}\) kg]
- A. 1.22 x 10\(^{-10}\)m
- B. 4.10 x 10\(^{-10}\)m
- C. 3.90 x 10\(^{-10}\)m
- D. 5.50 x 10\(^{-14}\)m
