The property which distinguishes longitudinal waves from transverse waves is the
A.ability to be refracted
B.need for a material medium
C.relative directions of oscillations and propagation
D.wavelength
E.the speed of propagation.
2.10 marks
Match the items in list A with responses in list B by writing the letter of the correct response beside the item number.
(i)
Internal resistance
1 mk
(ii)
Short sighted person
1 mk
(iii)
Thermistor
1 mk
(iv)
Eddy current
1 mk
(v)
Elasticity
1 mk
(vi)
Thermopile
1 mk
(vii)
Chromatic aberration
1 mk
((viii)
Secondary colours
1 mk
(ix)
Electrolysis
1 mk
(x)
Isotopes
1 mk
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7.0 marks
A radioactive source is known to emit one type of radiation only i.e. ᵯ, ᵯ or ᵯ. The source was placed in a holder as shown in fig. 4 below, first without a magnet and then a magnet was introduced. A detector was placed at positions 1, 2 and 3 and the count rates recorded in the table below.
Fig. 4
Counts per minute
Detector position
Magnet not present
Magnet present
1
26
295
2
300
28
3
28
26
((a)(i)
Define the background count.
3 mk
(b)
What is meant by the half-life of a radioactive element?
1 mk
((c)(i)
If the initial number of atoms in another sample of this element is $3.0 \times 10^{20}$, how many atoms will have decayed in 25 hours?
3 mk
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8.0 marks
How does a conductor differ from a semiconductor in terms of energy levels?
By means of a well labelled diagram, describe the electric and magnetic effects on the cathode beam deflection in a c.r.o.
What is a diode?
Make a sketch of the output voltage against time for half-wave rectification. explain why the output flows in pulses.
Describe and explain how a full-wave rectification is achieved by using two diodes.
((a)(i)
By means of a well labelled diagram, describe the electric and magnetic effects on the cathode beam deflection in a c.r.o.
3 mk
((b)(i)
Make a sketch of the output voltage against time for half-wave rectification. explain why the output flows in pulses.
2 mk
(c)
Describe and explain how a full-wave rectification is achieved by using two diodes.
2 mk
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Section C
3.2 marks
(c)
A simple weighing machine is made of a uniform bar 125 cm long and mass 5 kg and pivoted 2.5 cm from one end. Find the mass that must be suspended at the end of the long arm so as to balance a mass of 320 kg suspended at the end of the short arm.
2 mk
((a)(i)
what is the upward acceleration of the rocket?
2 mk
(b)
Calculate the acceleration of the rocket in 3(a) above when it has burned off 100 kg of fuel.
3 mk
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4.2 marks
A telescope of 5.0 m diameter reflector of focal length 18.0 m is used to focus the image of the sun. using the distance of the sun from the earth and diameter of the sun as 1.5 x 10^{11} m and 1.4 x 10^{9} m respectively, calculate the:
(a(i))
The cause of refraction of light when passing through transparent media.
1 mk
(c(i))
position of the image of the sun.
2 mk
(b(i))
Condition giving rise to critical angle and total internal reflection.
1 mk
(a(ii))
Position of image in concave mirror, of a very distant object.
1 mk
(b(ii))
Two principles in Physics used to make telescopes.
1 mk
(c(ii))
diameter of the image of the sun.
2 mk
(a(iii)
Cause for a blurred image in concave mirrors or convex lenses.
1 mk
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5.2 marks
A 200 g of liquid at 21°C is heated to 51°C by a current of 5 A at 6 V for 5.0 minutes. What is the specific heat capacity of the liquid?
(c)
A 200 g of liquid at 21°C is heated to 51°C by a current of 5 A at 6 V for 5.0 minutes. What is the specific heat capacity of the liquid?
2 mk
(b(i))
State Ohm’s law and two (2) of its limitations.
2 mk
(a(i))
Ampere
1 mk
(a(ii))
Coulomb
1 mk
(b(ii))
Determine the internal resistance of a cell and the value of R given that the p.d. of the cell in open circuit is 1.5 V, when connected to a 10 Ω resistor its p.d. becomes 1.0 V, but when connected to a resistor of R Ω the p.d. falls to 0.5 V
2 mk
(a(iii)
Volt
1 mk
(a(iv))
Ohm
1 mk
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6.3 marks
A copper pipe of length 100 cm at 15°C increases its length by 0.15% when a steam at 100°C passes through. Find the coefficient of linear expansivity of copper.
(c)
Define the coefficient of linear expansivity. A copper pipe of length 100 cm at 15°C increases its length by 0.15% when a steam at 100°C passes through. Find the coefficient of linear expansivity of copper.
3 mk
(b(i))
A gap is left between two successive rails.
1 mk
(a(i))
Differentiate between heat and temperature.
2 mk
(a(ii))
With the aid of a sketch graph explain the importance of the anomalous expansion of water.
2 mk
(b(ii))
A glass tumbler breaks when hot liquid is poured.
1 mk
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9.20 marks
Answer any two (2) questions from this section
((a)(i)
What do you understand by the following terms: Specific latent heat of fusion.
1 mk
(b)
State three (3) differences between evaporation and boiling.
3 mk
(c)
A tin contains water at 290 K and is heated at a constant rate. It is observed that the water reaches boiling point after 2 minutes and after further 12 minutes it is completely boiled away. Calculate the specific latent heat of steam.
5 mk
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10.20 marks
Answer any two (2) questions from this section
((a)(i)
Explain the meaning of Magnetic screening.
1 mk
(b)
Draw a circuit diagram of an electric bell and explain how it works.
4 mk
((c)(i)
Sketch the simple circuit for NPN transistor amplifier.
2 mk
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11.20 marks
Answer any two (2) questions from this section
((a)(i)
Define uniform velocity and uniform acceleration.
2 mk
(b)
Sketch the diagram of a body which starts from rest and accelerates uniformly for sometimes to a constant velocity and then maintains this velocity for a certain period of time before decelerating uniformly to a stop.
2 mk
((c)(i)
The car moving with a uniform velocity of 100 m/s is decelerated at 2.5 m/s$^2$ to a stop. Calculate the distance travelled by the car before it is brought to rest.
2 mk
