WAEC PHYSICS answers 2020 confirmed

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Part ii a) DescriptionTorque is the rotational equivalent of linear force. It is also referred to as the moment, moment of force, rotational force or turning effect, depending on the field of study. The concept originated with the studies by Archimedes of the usage of levers.

I)An object appears to be raised when paced under water.
ii)Pool of water appears less deep than it actually is.
III)If a lemon is kept in a glass of water it appears to be bigger when viewed from the sides of glass.
ii)It is due to refraction of light that stars appear to twinkle at night.

A progressive wave is defined as the onward transmission of the vibratory motion of a body in an elastic medium from one particle to the successive particle.

Part ii b) A free falling object is an object that is falling under the sole influence of gravity. Any object that is being acted upon only by the force of gravity is said to be in a state of free fall. … Free-falling objects do not encounter air resistance.

To confine the optical signal in the core, the refractive index of the core must be greater than that of the cladding. The boundary between the core and cladding may either be abrupt, in step-index fiber, or gradual, in graded-index fiber. Light can be fed into optical fibers using lasers or LEDs.

Pick two
Effects of refraction
I)An object appears to be raised when paced under water.
ii)Pool of water appears less deep than it actually is.
III)If a lemon is kept in a glass of water it appears to be bigger when viewed from the sides of glass.
ii)It is due to refraction of light that stars appear to twinkle at night.

: Part ii b) A free falling object is an object that is falling under the sole influence of gravity. Any object that is being acted upon only by the force of gravity is said to be in a state of free fall. … Free-falling objects do not encounter air resistance.

Mutual Inductance is the interaction of one coils magnetic field on another coil as it induces a voltage in the adjacent coil

In the previous tutorial we saw that an inductor generates an induced emf within itself as a result of the changing magnetic field around its own turns.
[8/28, 09:31] Temidayo: A progressive wave is defined as the onward transmission of the vibratory motion of a body in an elastic medium from one particle to the successive particle.

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2a.A typical flat-plate collector is a metal box with a glass or plastic cover (called glazing) on top and a dark-colored absorber plate on the bottom. … Sunlight passes through the glazing and strikes the absorber plate, which heats up, changing solar energy into heat energy.

2aii Solar thermal collectors heating water. Flat-plate and evacuated-tube solar collectors are mainly used to collect heat for space heating, domestic hot water, or cooling with an absorption chiller. In contrast to solar hot water panels, they use a circulating fluid to displace heat to a separated reservoir.

Theory-Answers.

(7)
(i)Coherence
(ii)Directionality
(iii)Monochromatic

(1)
Original length Lo= 3m
Extension e = 310 = 3*3= 9m
F×e
F=ke where k = 982.3NM-²
F=982.3*9=8,840.7N
The five that produce the extension F = 8.840.7N