Waec Physics 2011 Past Questions and Answers

Question 56:

• WAEC 2011

Explain why water in a narrow glass tube has a concave meniscus while mercury, in the same tube, has a convex meniscus.

Question 57:

• WAEC 2011

State three methods of polarizing an unpolarized light

Question 58:

• WAEC 2011

An electron of charge 1.60 x 10\(^{-19}\) C is accelerated under a potential difference of 1.0 x 10\(^5\) V. Calculate the energy of the electron in joules.

Question 59:

• WAEC 2011

The uncertainty in determining the duration during which an electron remains in a particular energy level before returning to the ground state is 2.0 x 10\(^{-9}\)s. Calculate the uncertainty in determining its energy at that level. (\(\frac{h}{2 \pi}\) = h = 1.054 x 10\(^{-34}\)Js)

Question 60:

• WAEC 2011

(a) What is a vector quantity?
(b) Three vectors 3 ms\(^{-1}\) N 45° W, 12 ms\(^{-1}\)W and 5 ms\(^{-1}\)S act at a point.
(i) Sketch a vector diagram to illustrate the given information.
(ii) Calculate the resultant of the vectors.
(c) In a laboratory experiment to determine the force constant of a spiral spring, the mass or, the spring was varied and the corresponding extensions were measured and recorded as shown in the table below.

Mass M/g	Weight W/N	Extension e/cm
50100150200250		6.511.015.020.025.0

(i) Copy and complete the table. (Take g = 10 ms\(^{-2}\))
(ii) Plot a graph with weight, W, on the vertical axis and extension, e, on the horizontal axis.
(iii) Using the graph, determine the force constant of the spring.
(iv) Determine the natural length of the spring if its length was 38.0 cm when loaded with 250 g mass.