The magnetic field of a magnet is an invisible field which is created by magnetism. The force for magnets to attract other objects is caused by moving electrons. Magnets are made by using electrical and mechanical methods. A temporary magnet can be made by passing electricity through a coil.
Moving _____ is the cause of magnets repelling or attracting each other or other objects.
There is a variety of materials that are used to make components of electrical circuits. These materials have good electrical conductivity. Inspite of having the largest conductivity among metals, silver is not used to make electric wires. Aluminium and copper are generally used to make electric wires. Not only conductors, insulators are also important. The electrical wires are covered with plastic and rubber like materials. This is used to prevent short circuit and also to protect the user.
What kind of materials are used to make electrical wires in an electric circuit?
D All of these
The speed of a body gives us an idea of how slow or fast that a body is moving. Speed of a body is the distance travelled by it per unit time. The SI unit of speed is metre per second. It is a scalar quantity. The speed of a running car at any instant of time is shown by an instrument called 'speedometer' and the distance travelled by a car is measured by another instrument called 'odometer'.
If an object is moving with speed (S) in time (t), then, the distance (d) will be
A d = S × t
D None of these.
Two bricks each of same dimensions are placed on level ground. Surface area of end of each brick is 40 cm2 and the surface are of base of each brick is 150 cm2. Each brick weigh 40 N.
If both bricks are placed as shown then pressure exerted by both bricks on ground is
A 100 N m–2
B 126 N m–2
C 150 N m–2
D 126 N m–2
The diagram is not given.
Assertion : The gravitational force makes the earth move around the sun and also makes the moon go around the earth.
Reason : Every objects in the universe exert a force on other objects.
In the following questions, a statement of assertion is followed by a statement of reason. Mark the correct choice as :
A If both assertion and reason are true and reason is the correct explanation of assertion
B If both assertion and reason are true but reason is not the correct explanation of assertion
C If assertion is true but reason is false
D If assertion is false but reason is true.
The answer is A, even the solution is justifying it.