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Orezy5:
PHYSICS

Corrections will be posted by 6pm tomorrow.


1. A convex mirror produces an image Which is one quarter the size of an object placed in front of it. If the radius of curvature of the mirror is 32cm, calculate the distance between the object and its image.

2. An object is located at a distance of 20cm from a concave mirror of radius of curvature 30cm. Calculate the distance between the object and its image.

3. For an object placed 6cm from a diverging lens of focal length 18cm, the image is ____

A. 4.5cm behind The lens
B. 4.5cm in front of the lens
C. 9cm in front of the lens
D. 9cm behind the lens


4. Determine the power of a concave lens with focal length 25cm.

MrEDUCATION:
Quick hot Revision Tips in PHYSICS.


# Power is measured in Watts in the laboratory but it is measured in Horsepower in the industry. One Horsepower equals 0.746 Kilowatts.


# An hectare is the unit for measuring an area of land. One hectare equals 10000square meters.


# The reading accuracy of a metre rule is 1mm or 0.1 cm. The reading accuracy of Vernier callipers is 0.01cm.Micrometer Screw Gauge has its reading accuracy as 0.001cm.


# Mass is measured with a beam balance or a chemical balance while weight is measured with a spring balance.


# In calculating relative motion, if the two bodies in consideration are moving in the same direction, you SUBTRACT their velocities, but if they are moving in opposite directions, you ADD their velocities.


# LAWS OF FRICTION.
> Friction opposes motion.
> Friction is directly proportional to reaction force or normal reaction.
> Friction is independent on the surface area in contact.
> It is dependent on the nature of the surfaces in contact (i.e. whether rough or smooth)
> Friction is independent of the magnitude of relative motion between the two surfaces.


# IN CIRCULAR MOTION
> Angular displacement,(theta) = 2π x n(number of revolutions)
> Linear displacement, S = (theta) x r (distance traveled from one position to another in the circular path)
> Angular speed/velocity(W) = angular displacement (theta) over time taken.
> Linear velocity = Linear displacement (S) over time taken.
> Angular acceleration = angular velocity over time taken.


# Centripetal Force = mv²/r = mw²r.


# Centrifugal Force is the opposite of centripetal force.


# Work = Force x Displacement = mass x height x acceleration due to gravity.


# Energy is the capacity or ability to do work.


# Potential Energy = mgh.


# Kinetic Energy = ½mv².


# Area expansivity = 2 x Linear expansivity.


# Volume expansivity = 3 x Linear expansivity.


# The real (or absolute) cubic expansivity of a liquid is the increase in volume per unit volume per degree rise in temperature WHILE The apparent cubic expansivity of a liquid is the increase in volume per unit volume per degree rise in temperature WHEN THE LIQUID IS HEATED IN AN EXPANSIBLE VESSEL.


# Most liquids expand when heated and contract when cooled. Water is an exception because it contracts on cooling from any temperature until at 4°C when it starts to expand if cooled below this temperature. Thus, water expands(rather than contract) when cooled from 4°C to 0°C. Hence, a given mass of water has its least volume (and therefore its highest density) at 4°C. This is known as the anomalous expansion of water which can be verified using the Hope’s experiment.


# Radiation can be detected by a radiometer or a thermopile.


# A black material or surface is both a better radiator and absorber of heat than a polished surface.


# The three modes of heat transfer are brought into good application in the Thermos flask. It has a double-walled glass vessel with a vacuum between the walls. The vacuum reduces heat lost or gain by conduction or convection. The double walls of the glass vessel are silvered on the vacuum side to minimize the loss or gain of radiant heat. The bottom of the flask rests on a cork support and the mouth of the flask is also closed by a cork stopper which is a poor conductor hence reducing heat loss or gain by conduction, evaporation and convection if the flask contains hot liquid.



TO BE CONTINUED…

DrOptimistic:
Thanks very much. God bless you. Thanks for always helping we the aspirants

MrEDUCATION:
300+ RECORD BREAKERS in JAMB Series.

Quick hot Revision Questions in PHYSICS.

Ten questions to be answered in 20 minutes!
The CORRECT ANSWERS with their EXPLANATIONS will be released in 24 hours!


1 : A bead travelling on a straight wire is brought to rest at 0.2m by friction. If the mass of the bead is 0.01Kg and the coefficient of friction between the bead and the wire is 0.1, determine the work done by friction.
A ) 0.0002 Joules.
B ) 0.002 Joules.
C ) 20 Joules.
D ) 200 Joules.
[g ≈ 10m/s²]


2 : On top of a spiral spring of force constant 500N/m is placed a mass of 0.003Kg. If the spring is compressed downwards by a length of 0.02m and then released, calculate the height to which the mass is projected.
A ) 8m
B ) 4m
C ) 2m
D ) 1m
[g ≈ 10m/s²]


3 : A test tube of radius 1.0cm is loaded to 8.8g. If it is placed upright in water, find the depth to which it would sink.
A ) 2.8 cm
B ) 5.2 cm
C ) 25.5 cm
D ) 28.0 cm
[g ≈ 10m/s², density of water = 1000Kg/m²]


4 : If an object just begins to slide on a surface inclined at 30° to the horizontal, the coefficient of friction is _____?
A ) Surd 3
B ) Surd 3/2
C ) 1/surd 2
D ) 1/surd3


5 : A force of 100N is used to kick a football of mass 0.8Kg. Find the velocity with which the ball moves if it takes 0.8 seconds to be kicked.
A ) 32m/s
B ) 50m/s
C ) 64m/s
D ) 100m/s


6 : A piece of stone attached to one end of a string is whirled round in a horizontal circle and the string suddenly cuts. The stone will fly off in a direction ______
A ) perpendicular to the circular path.
B ) parallel to the circular path.
C ) tangential to the circular path.
D ) towards the center of the circle.


7 ) By what factor will the size of an object placed 10cm from a convex lens be increased if the image is seen on a screen placed 25cm from the lens?
A ) 15.0
B ) 2.5
C ) 1.5
D ) 0.4


8 : An open pipe closed at one end produces its first fundamental note. If the velocity of sound in air is V and L is the length of the pipe, the frequency of the note is ____?
A ) 2V/L
B ) V/5L
C ) V/4L
D ) V/2L


9 : If an object is placed between two parallel plane mirrors with their reflecting surfaces facing each other, how many images of the object will be formed?
A ) Infinite .
B ) Eight.
C ) Four.
D ) Two.


10 : The operation of an optical fibre is based on the principle of ______?
A ) dispersion of light.
B ) interference of light.
C ) refraction of light.
D ) polarization of light.

300+ RECORD BREAKERS in JAMB Series.

Quick hot Revision Questions in PHYSICS.

Ten questions to be answered in 20 minutes!

The CORRECT ANSWERS with their EXPLANATIONS will be released in 24 hours!


1 : A bead travelling on a straight wire is brought to rest at 0.2m by friction. If the mass of the bead is 0.01Kg and the coefficient of friction between the bead and the wire is 0.1, determine the work done by friction.
A ) 0.0002 Joules.
B ) 0.002 Joules.
C ) 20 Joules.
D ) 200 Joules.
[g ≈ 10m/s²]

The answer is B because in calculating the work done by friction, using the formula; Work done(W) = Frictional Force(F) x displacement (S).But coefficient of friction (U) = Frictional force/Reaction force(mg). [.: F = Umg] . Substituting [F = Umg] in the initial equation, we have that : Work done = U x mg x S = 0.1 x 0.01 x 10 x 0.2 = 0.002 Joules.


2 : On top of a spiral spring of force constant 500N/m is placed a mass of 0.005Kg. If the spring is compressed downwards by a length of 0.02m and then released, calculate the height to which the mass is projected.
A ) 8m
B ) 4m
C ) 2m
D ) 1m
[g ≈ 10m/s²]

The correct answer is C because, from the principle of energy conservation, the elastic potential energy that was stored in the compressed spring (½ke²) was transformed into gravitational potential energy (mgh) when the spring stretches. [.: ½ke² = mgh] .We make h the subject of the formula to find the height, .: h = (k x e²)/(2 x m x g) = (500 x 0.02 x 0.02)/(2 x 0.005 x 10) = 2meters.

3 : A test tube of radius 1.0cm is loaded to 8.8g. If it is placed upright in water, find the depth to which it would sink.
A ) 2.8 cm
B ) 5.2 cm
C ) 25.5 cm
D ) 28.0 cm
[g ≈ 10m/s², density of water = 1000Kg/m²]

The answer is A because from Archimedes principle, upthrust in water is equal to weight of water displaced. i.e. Density x Volume x acceleration due to gravity(g) = mass x g. But Volume(V) = Area x height(depth). Substitute for V in the initial equation and cancel out g on both sides, we have : Density(D) x Area(A) x height(h) = mass(M). [A = πr² = Π x 0.01² ≈ 0.0003142]. Also, M = 8.8g = 0.0088kg.We are looking for height (depth). Therefore, h = M/(D x A) = 0.0088/(1000 x 0.0003142) ≈ 0.028meters = 2.8cm.


4 : If an object just begins to slide on a surface inclined at 30° to the horizontal, the coefficient of friction is _____?
A ) Surd 3
B ) Surd 3/2
C ) 1/surd 2
D ) 1/surd3
The correct answer is D because the coefficient of friction(U) = F/R = (sin theta)/(cos theta) = tan theta. Here, theta = 30°. Therefore, U = tan 30° = 1 over surd 3.

5 : A force of 100N is used to kick a football of mass 0.8Kg. Find the velocity with which the ball moves if it takes 0.8 seconds to be kicked.
A ) 32m/s
B ) 50m/s
C ) 64m/s
D ) 100m/s

The correct answer is D because from the formula for Force(F),which is; F = ma, but a = V/t. Therefore, F = mv/t. To find Velocity, V = Ft/m = (100 x 0.8 )/0.8 = 100m/s.


6 : A piece of stone attached to one end of a string is whirled round in a horizontal circle and the string suddenly cuts. The stone will fly off in a direction ______
A ) perpendicular to the circular path.
B ) parallel to the circular path.
C ) tangential to the circular path.
D ) towards the center of the circle.

The correct answer is C because when the string suddenly cuts or breaks, the stone no longer rotates around its center of rotation but will move directly away from it and continue to follow its path of inertia. That is, it will continue to move in the direction in which it was moving at the moment the string broke because there is no more centripetal force to keep it in the circular path.

7 ) By what factor will the size of an object placed 10cm from a convex lens be increased if the image is seen on a screen placed 25cm from the lens?
A ) 15.0
B ) 2.5
C ) 1.5
D ) 0.4

The answer is B because magnification = image distance/object distance = 25cm/10cm = 2.5


8 : An open pipe closed at one end produces its first fundamental note. If the velocity of sound in air is V and L is the length of the pipe, the frequency of the note is ____?
A ) 2V/L
B ) V/5L
C ) V/4L
D ) V/2L

The correct answer is C because the Fundamental Frequency of a closed pipe is given by V/4L.


9 : If an object is placed between two parallel plane mirrors with their reflecting surfaces facing each other, how many images of the object will be formed?
A ) Infinite .
B ) Eight.
C ) Four.
D ) Two.

The correct answer is A because when two mirrors are placed parallel to each other and an object is placed between them, the number of images formed is infinite.


10 : The operation of an optical fibre is based on the principle of ______?
A ) dispersion of light.
B ) interference of light.
C ) refraction of light.
D ) polarization of light.

The correct answer is C because optical fibre is used to transmit very strong optical signal over a long distance and it works by the principle of refraction or total internal reflection.

Orezy5:
PHYSICS

Corrections will be posted by 6pm tomorrow.


1. A convex mirror produces an image Which is one quarter the size of an object placed in front of it. If the radius of curvature of the mirror is 32cm, calculate the distance between the object and its image.

2. An object is located at a distance of 20cm from a concave mirror of radius of curvature 30cm. Calculate the distance between the object and its image.

3. For an object placed 6cm from a diverging lens of focal length 18cm, the image is ____

A. 4.5cm behind The lens
B. 4.5cm in front of the lens
C. 9cm in front of the lens
D. 9cm behind the lens


4. Determine the power of a concave lens with focal length 25cm.

Probity567:
That number 3 answer is D because carbon iv sulphide is a solvent for sulphur while ethanol is a solvent for iodine , that is while we have a tincture of iodine

Doneze:
Good evening, had a first degree in Optometry applying for D.E UI Medicine. Do they write post D.E exam?

Doneze:
OK.. So what the process like, how many do they admit for D.E?

majormofor:
you go to the admin office submit ur credentials, register for DE with jamb and that's all

Orezy5:
PHYSICS

Corrections will be posted by 6pm tomorrow.


1. A convex mirror produces an image Which is one quarter the size of an object placed in front of it. If the radius of curvature of the mirror is 32cm, calculate the distance between the object and its image.

2. An object is located at a distance of 20cm from a concave mirror of radius of curvature 30cm. Calculate the distance between the object and its image.

3. For an object placed 6cm from a diverging lens of focal length 18cm, the image is ____

A. 4.5cm behind The lens
B. 4.5cm in front of the lens
C. 9cm in front of the lens
D. 9cm behind the lens


4. Determine the power of a concave lens with focal length 25cm.

pentane05:
Hello guys.. Please which month is university of Ibadan will start selling their direct entry form?

Doneze:
Credentials like

DrEmmy01:
Why is this thread so dry

DrOptimistic:
With time, it will become active

DrEmmy01:
I hope so, I'm really hoping on this thread.

ORIJIN201:
So I scored 217 and I'm going for chemistry

Nltaliban:
You stand a fair chance

Go prepare for you postume