Part B of Physics Third Term 2024/2025 Exams

1a). Differentiate between

i). Pascal (Pa) and Nm^-2 as units of Pressure                                                                       (2 marks)

ii). Rays and beams of light                                                                                             (2 marks)

iii). Heat energy and temperature                                                                                     (2 marks)

iv). Transverse and longitudinal waves                                                                           (2 marks)

v). luminous and non-luminous objects                                                                           (2 marks)

1b). An electric heater, rated 15 V 40 W, fitted into a metal block supplies heat to the block of mass 1.5 kg and specific heat capacity of 460JKg-1K-1. Calculate the temperature rise in the block if the current flows for 10 minutes.                                                                        (3 marks)

1c). 1200cm3 of a gas is collected at 370C and 600mmHg.Convert this volume to stp.

(3 marks)

1d). With the aid of a fully labeled diagram, describes the laws of reflection.                     (4 marks)

2ai). Differentiate between the manometer and the barometer.                                  (2 marks)

2aii). Mention any two types of barometer and their uses                                                    (4 marks)

2aiii). Mention one advantage that each has over the other.                                  (2 marks)

2b). A gas occupies 5L at 2 atm pressure and 400K. How many moles of gas are present?

                                                                                                                                           (2 marks)

3a). Define the following wave terms;

i.                Amplitude                                                                                              (1 mark)

ii.              Frequency                                                                                               (1 mark)

iii.           Wavelength                                                                                            (1 mark)

iv.            Period                                                                                                     (1 mark)

3b). If V is the velocity of a wave, λ is its wavelength, f its frequency, and T is the period. Show the relationships between;

i.                   f and T                                                                                                                 (1 mark)

ii.                 V, f and λ, and                                                                                                  (1 mark)

iii.               by extension, proof that λ = VT                                                                        (2 marks)

3c). A wave on a string travels at 20m/s and has a frequency of 5Hz. What is its wavelength?                                                                                                                                   (2 marks)

4a). What do you understand by the term rectilinear propagation of light?            (2 marks)

4b). Describe one experiment that proves the term mentioned in 4a) above.            (4 marks)

4c). The height of an object placed at a distance of 60 cm from the hole of a pinhole camera is 15 cm. If the length of the camera is 10 cm, calculate the magnification produced by the camera and the height of the image.                                                      (4 marks)

5a). State the characteristics of images formed by a plane mirror.                                  (5 marks)

5b). Explain the formation of regular (specular) reflection and diffuse (scattered) reflection using diagrams with sufficient details.                                                                            (5 marks)