# Waec Marking Scheme For Physics In 2020 + Practicals

WAEC has ended and now it is time to start marking students’ scripts.
Each subject has their own particular grading system  which the examiners use as a guide to know how many marks a particular answer should be rewarded.
This is what determines the difference between A and B.
Some students may be able to write their answers perfectly but if it is not up to the marking scheme, they may loose some important marks.
In this post i will explain the waec marking scheme for physics practical.
Every physics examination in waec are marked according to the marking scheme provided by the council.
This post has to deal with the 2020 waec marking scheme for physics .
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The physics examination in waec is categoralized into three parts which are : Paper 1, 2 and 3. Physics paper 1 which is the objective test consists of 50 questions for 50 marks, that is;  each question carries one mark and the time for this objective test is 1 hour 15 minutes.
You are just to pick the correct answer in the options below the questions.
Sample questions on the objective test are provided below:
1. The S. I unit of sound energy is
A.  Hz.
B.  cd.
C. dB.
D. J.
2. The property of a body to remain at rest or to continue in a uniform motion, in a straight line is called
A. Momentum.
B. Inertia
C. Impulse
D. Energy
3. A dam is able to hold a large quantity of water because its wall is
A. Thickest at the top.
B. Thickest at the middle.
C. Thickest at the bottom.
D. Of the same thickness throughout.
4. Two plane mirrors are inclined to each other such that an object placed between them has 11 images. Determine the angle of inclination.
A. 30°
B. 45°
C. 60°
D. 90°
5. The ice point on the absolute scale of temperature is
A. 0 K
B. 32 K
C. 100 K
D. 273 K

## Waec physics paper 2

Physics 2 consists of 15 theory questions, but sometimes it consists of 12 questions.
These questions are further divided into PART I and PART II or SECTION A and SECTION B. PART I contains 7 questions, but may be 10 questions in some cases.
The PART I is simpler than the second part or section. PART II consists of 5 questions that need full and detailed answers.
PART I questions is for 20 marks, while PART II goes for 40 marks. Candidates are to answer five questions in PART I and 3 questions in PART II.
The total time for paper 2 theory questions is is 1 hour 45 minutes. The sample questions for PART I and II are provided below:

PART I
1. State three methods of polarising an unpolarised light.
2. (a) Define diffusion (b) State Graham’s law of diffusion.
3. Explain why water in a narrow glass tube has a concave meniscus while mercury, in the same tube, has a convex meniscus.
4. A particle is projected horizontally at 10 m/s from a height of 45m. Calculate the horizontal distance covered by the particle before hitting the ground. [g = 10m/s²]
5. List three observations in support of the de Broglie’s assumptions that moving particles behave like waves.
6. State the dimensions of: (a) power; (b) momentum; (c) density
7. Sketch a graph to show the I-V characteristics of p-n junction diode.
8. (a) What is Doppler effect? (b) State one practical situation in which Doppler effect is experienced
9. Explain how audible beats arise when two tuning forks of slightly different frequencies f1 and f2 are sounded together
10. State Kirchhoff’s laws of electrical network.
PART II
11(a)(I) With the aid of a labelled diagram describe the mode of operation of a modern X-ray tube.
(II) State the energy transformations that take place during the operation of the X-ray tube.
(b) Define, as applied to X-rays, the following terms: (I) hardness
(II) intensity
(c) State (I) four uses of X-rays;
(II) hazard of over-exposure to X-rays in a radiological laboratory.

### Waec physics practical marking guide (paper 3)

Physics paper 3 is majorly the practical examination scheme done to test the knowledge of the candidates on the practical aspect of physics.
It consists of 3 questions and the candidates are to answer two questions only.
Each question carries 25 marks, the two questions sum up to 50 marks.
The specimens to be used for the practical are provided for the candidates and questions about the practical are asked.
The time for the paper 3 (practical) is 2 hours 45 minutes.
The detailed description offered the apparatus used in the experiment are not required.
The record may be kept in pencil provided it can be read clearly.
The waec physics practical examination are marked under different sub-headings:
1. Observation from physics practical  table : Observations should be recorded in tabular form. If they are not tabulated, students earn no marks.
Fundamental units must be shown on the column for each of it, for example; seconds (s), kilogram (kg), volts (V), metre (m), amperes (A), volume (cm³), must be written, no units or wrong units attract the lost of half mark per column.
Fundamental values must be recorded to at least two decimal places, inconsistent decimal place attract the lost of half mark.
No decimal point at all means no score for that particular column. Calculated values must be recorded to at least three decimal places.
2. Graph : Graph must occupy at least one third of the graph page, for the graph to be reasonable, origin is part of the graph. Axis must be well labelled.
Scales must be reasonable and plottable. Scales using multiples or sub-multiples of prime numbers such as 3, 7, 9, 13 are not accepted. Points should be plotted correctly to nearest ½ square on both axis.
3. Slope : The large right angle triangle implies that it occupies one-third of the graph. The change in horizontal axis must be correctly read. The change in the vertical axis must be correctly read and recorded.
4. Deductions : This is about substituting the slope in the intercept, C, and some other parameters into particular equations.
5. Precautions : This must be stated in an acceptable language, acceptable language means that the candidates should use past tense because the precautions are what the students ensured or avoided when performing the experiment (practical).

## Practical precautions

Some common precautions in electricity experiments include :
1. I removed the key when readings were not taken.
2. I avoided error in reading the metre rule, voltmeter, ammeter, etcetera.
3. I ensured tight connections and clean terminals.
4. I noted and corrected the zero error of the ammeter, voltmeter, metre rule, etcetera.
5. I avoided sliding the jockey of the potentiometer.
Some common precautions in light experiments include :
1. I ensured neat traces.
2. I ensured that the lens is vertically placed in the holder.
3. I ensured that the pins are vertically placed.
Some common precautions in mechanics experiments are :
1. I avoided draught.
2. I avoided conical oscillations.
3. I ensured firm suspension of the pendulum.
4. I ensured that the suspended mases do not touch the table.
5. I noted and corrected the zero error of the metre rule, stop watch, etcetera.
A sample question on physics practical, paper 3 is provided below :
1(a)
(I) You are provided with two metre rules and other necessary apparatus.
(II) Place one of the rules on a knife edge and determine its centre of gravity C. Mark this position with a piece of chalk.
(III) Read and record the mass Mr of the metre rule written on the reverse side of it.
(IV) Attach the mass M=100g firmly to the rule AB at C using sellotape.
(v) Suspend the metre rule by two parallel threads of length h=40cm each at the 10cm and 90cm marks. Ensure that the graduated face of the metre rule is facing upwards.
(vi) Set the rule AB into a small angular oscillation about the vertical axis through its centre of gravity.
(vii) Determine the time t for 20 complete oscillations. Evaluate the period T and T².
(viii) Read and record the value of d in metres.
(ix) Keeping d constant throughout the experiment, repeat the procedure for other values of h = 50, 60, 70 and 80cm. In each case determine the corresponding values of t, T and T². Tabulate your readings.
(x) Plot a graph of T² on the vertical axis and h on the horizontal axis.
(xi) Determine the slope, S, of the graph.
Evaluate k = s/Q
Where Q = 2/25d²
(xii) State two precautions taken to ensure accurate results.
(b) (I) Define the term couple as it relates to rotational and oscillatory systems.
(II) Give two practical applications of a couple in everyday life.
And that is the waec 2020 marking guide or scheme for physics practical.
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