Nabteb 2022 Physics Essay And Obj Answers

Pressure on surface is defined as the average force or weight exerted per unit area.


Density of a substance is the mass of the substance per unit volume.The unit of density is kg/m³. On the other hand, Relative density of a substance is the ratio of the mass of a given volume of a substance to the mass of an equal volume of water. Relative density has no unit

Relative Density = Weight in Air – Weight in liquid/ Weight in the air – Weight in water

Weight in Air = 10N
Weight in Liquid = 4N
Weight in water = 6N
R.D = (10 – 4)/(10 – 6) = 6/4 = 1.5
:. Relative Density = 1.5

Capillarity is the tendency of a liquid in a capillary tube or absorbent material to rise or fall as a result of surface tension.

(i) Sucking of water by the towel
(ii) The rise of kerosene in the wick of a lantern
(iii) Sucking of ink by the blotting paper

(i) Change in volume of liquid with temperature
(ii) Change in resistance
(iii) Expansion of solids

(i) It should be visible
(ii) It should have uniform thermal expansion
(iii) It should have a low freezing point
(iv) It should have a high boiling point

(i) All gases are made up of molecules that are constantly and persistently moving in random directions.
(ii) When a gas sample is kept in a container, the molecules of the sample do not exert any force on the walls of the container during the collision.
(iii) The time interval of a collision between two molecules, and between a molecule and the wall is considered to be very small.
(iv) All the collisions between molecules and even between molecules and walls are considered to be elastic.

Charles law states that the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature if the pressure remains constant.
V ∝ T (at constant pressure)

Boyle’s law states that the volume of a fixed mass of a gas varies inversely to the pressure upon it, provided the temperature remains constant.
P∝1/V i.e PV = Constant

Using pressure law
P₁/T₂ = P₂/T₂
T₁= (273+30)= 303K
T₂= (273+80)= 353K

990/303 = P₂/353
P₂= (990×353)/303
P₂= 1153.4 mmHg

A musical note is a sound which is produced due to a mixture of several frequencies

(i) String instruments: Piano, Guitar
(ii) Pipe instruments: Clarinet, Saxophone
(iii) Percussion instruments: Drum, gong

(i) Density of the Medium
(ii) Temperature of the medium

This is because sound has a wavelength on the order of 1 meter and diffracts very easily. It involves both diffraction and reflection of sound.


V= 2f(L₂-L₁)
V= 2 x 478(0.75 – 0.40)
V= 2 x 478(0.35)
V= 334.6m/s

(i) V is an instantaneous voltage which is the induced voltage flowing at any instant during a cycle.
(ii) V₀ is the peak or maximum voltage which is the highest point or highest value of voltage for any voltage waveform.

Root mean square current is that steady current which will develop the same quantity of heat at the same time in the same resistance.

Inductive reactance is the resistance offered in an A.C circuit which is purely inductive.

Capacitive reactance is the resistance offered in an A.C circuit which is purely capacitive.


(i) XL = 2πFL
XL = 2×3.14x50x0.9
XL = 282.6Ω
. : Inductive reactance = 282.6Ω

(ii) Xc = 1/(2πFC)
Xc = 1/(2×3.14x50x2x10-⁶)
Xc = 1592.4Ω
. : Capacitive reactance = 1592.4Ω

(ii) Z = √[R²+(XL – XL)²]
Z = √[300² +(1592.4 – 2826)²]
Z = 1342.7Ω
. : Impedance = 1342.7Ω

(iv) I = V/Z
I = 240/1343.7
I = 0.18A
. : Current in the circuit = 0.18A

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