Question Library

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.

Which of the following liquids has the highest surface tension?

The nucleon and proton numbers of a neutral atom of an element are 238 and 92 respectively. Determine the number of neutrons in the atom.

The area under a velocity-time graph represents

When ultraviolet light is incident on certain metallic p articles are emitted. These particles are called

The graph above illustrates the variation of temperature \(\theta\) with time (t) for a solid that is being heated. Which processes take place at segments P and Q respectively?

(a) (i) Define atomic spectra. (ii) Differentiate between emission spectra and absorption spectra. (b) The diagram above illustrates an electron transition from energy level n = 3 to n = 1. Calculate the: (i) energy of the photon (ii) frequency of the photon (ii) wavelength of the photon [h = 6.6 x 10\(^{-34}\)J s, c = 3.0 x 10\(^8\) ms\(^{-1}\); 1 ev = 1.6 x 10\(^{-19}\) J] c)(i)Differentiate between soft x-rays and hard x-rays (ii) Draw the circuit symbol for a p-n junction diode. (iiii) Give the reason for doping a semiconductor material

Two bodies of masses 3.0 kg and 2.0 kg are separated by a distance of 50 cm. Calculate the force of attraction between them. [G = 6.67 x 10\(^{-11}\) Nm\(^2\) kg\(^2\)]

The diagram above illustrates an object moving in a circular path at a constant speed. Which of the arrows indicates the direction of linear velocity?

In the diagram above, the time taken to trace a wave between P and Q is?

Which of the following materials does not serve as a safety device in electrical circuits?

You are provided with a stopwatch, a meter rule, a split cork, retort stand and clamp, a pendulum bob, a piece of thread, and other necessary apparatus. i. Place the retort stand on a laboratory stool. Clamp the split cork. ii. Suspend the pendulum bob from the split cork such that the point of support P of the bob is at height H = 100cm above the floor Q. The bob should not touch the floor and H should be kept constant throughout the experiment. iii. Adjust the length of the thread such that the center A of the bob is at a height y= AQ= 20cm from the floor. iv. Displace the bob such that it oscillates in a horizontal plane. v. Take the time t for 20 complete oscillations. vi. Determine the period T of oscillation and evaluate T vii. Repeat the procedure for four other values of y = 30cm, 40cm, 50cm, and 60cm. In each case, determine T and T. viii. Tabulate the results. ix. Plot a graph of T on the vertical axis and y on the horizontal axis, starting both axes from the origin (0,0). x. Determine the slope, s, of the graph and the intercept c on the vertical axis. xi. If in this experiment SR= c, calculate R. x. State two precautions taken to ensure accurate results. (b) i. The bob of a simple pendulum is displaced a small distance from the equilibrium position and then released to perform simple harmonic motion Identify where its: (\(\propto\)) kinetic energy is maximum (\(\beta\)) acceleration is maximum ii. An object of weight 120N vibrates with a period of 4.0s when hung from a spring. Calculate the force per unit length of the spring. [g= 10ms\(^{-2}\), \(\pi\)=3.142]

You are provided with a converging lens and holder, a screen, a ray box containing an illuminated object pin, and a meter rule.(See illustration above) i. Place the lens in its holder such that it is facing a distant object seen through a well-lit laboratory window. Move the screen to and fro until a sharp image of the distant object is formed on it. Measure the distance, \(f_0\), between the screen and the lens. ii. Clamp the meter rule securely to the table. Place the illuminated object pin at the end R of the meter rule. iii. Place the lens at a position P such that X = RP = 20cm. iv. Move the screen to a position Q to receive a sharp image of the object. Measure the distance Y = PQ. v. Evaluate Z = (X+Y) vi. Repeat the procedure for five other values of x = 25cm. 3Ocm, 35cm, 40cm and 45cm. In each case, record X,Y and evaluate Z. vii. Tabulate the results. viii. Plot a graph with Z on the vertical axis and X on the horizontal axis. Draw a smooth curve through the points. ix. Determine from your graph the minimum value of Z=\(Z_0\) and its corresponding distance x. Evaluate W = ½ (\(\frac{Z_0}{4} + \frac{X_0}{2}\)) xi. State two precautions taken to ensure accurate results. (b) i. Draw a ray diagram to show how a Convex lens forms an image of magnification less than one. ii. Name two pairs of features in the human eye and a lens camera that performs similar functions.

You are provided with a battery of e.m.f. E, a key K, a voltmeter, a standard resistor \(R_0\) = 2\(\Omega\), a resistance box R, and some connecting wires. i. Measure and record the e.m.f. E of the battery. i. Set up a circuit as shown in the diagram above with the key open. iii. Set the resistance on the resistance box to R 22. iv. Close the key, read and record the potential difference V on the voltmeter. v. Evaluate V\(^{-1}\) vi. Repeat the procedures for five other values of R = 5\(\Omega\) 10\(\Omega\),12\(\Omega\),15\(\Omega\) and 20\(\Omega\). In each case, record V and evaluate V\(^{-1}\) vii. Tabulate the results. viii. Plot a graph with R on the vertical axis and V\(^{-1}\) l on the horizontal axis, starting both axes from the origin (0,0). ix. Determine the slope, s, of the graph and the intercept c on the vertical axis. x. Calculate \(\propto\) and \(\beta\) from the equations s = \(R_0\) \(\propto\) and c= - (\(R_0\)+B). xi. State two precautions taken to obtain accurate results.

You are provided with a battery of e.m.f. E, a key K, a voltmeter, a standard resistor \(R_0\) = 2\(\Omega\), a resistance box R, and some connecting wires. i. Measure and record the e.m.f. E of the battery. i. Set up a circuit as shown in the diagram above with the key open. iii. Set the resistance on the resistance box to R 22. iv. Close the key, read and record the potential difference V on the voltmeter. v. Evaluate V\(^{-1}\) vi. Repeat the procedures for five other values of R = 5\(\Omega\) 10\(\Omega\),12\(\Omega\),15\(\Omega\) and 20\(\Omega\). In each case, record V and evaluate V\(^{-1}\) vii. Tabulate the results. viii. Plot a graph with R on the vertical axis and V\(^{-1}\) l on the horizontal axis, starting both axes from the origin (0,0). ix. Determine the slope, s, of the graph and the intercept c on the vertical axis. x. Calculate \(\propto\) and \(\beta\) from the equations s = \(R_0\) \(\propto\) and c= - (\(R_0\)+B). xi. State two precautions taken to obtain accurate results.