which is the world's first magnet

When magnet is suspenseded freely it always shows which direction

Only natural magnet known to man

Permanent magnets is made up of

Simple voltaic cell was discovered by

Simple voltaic cell was discovered in

Daniel cell was discovered by

Daniel cell was discovered in

Modification of simple voltaic cell is

Dry leclanche cell was discovered by

Dry leclanche cell developed in

cell which converts chemical energy into electrical energy and cannot function once the chemical are exhausted is called

A cell in which electrical energy is stored in the form of chemical energy such that when required the chemical energy its reconverted into electrical energy is called

secondary cell was invented in

Secondary cell was invented by

Branch of physics which deals with the relationship between electricity and magnetism is called

When electric current flows around iron nail or an iron bar is it called

When a magnetic field is charged near conductor, a current is produced in it this was discovered by

When a magnetic field is charged near conductor, a current is produced in it this was discovered in

Phenomenon due to which a changing magnetic field within a closed coil induces an electric current is the coil is called

Current produced in a closed coil when the magnetic lines are forced rapidly change within it is called

Principle of electromagnetic Induction is used in generating electric current by a device is called

The property of light travelling in a straight path

when a ray of light travells from a less denser medium to high denser medium is

when a ray of light travells from a higher denser medium to lower denser medium is

when the ray of light strikes the surface of separation of two media at an angle of 90° it

incident ray,refracted ray and normal lie in the

light consists of which type of waves

best reflector of light

Bundle of light ray is called

It is a line at a right angle to the mirror surface at the point of incidence

An angle made by incident ray and with normal at the point of incidence is called

Angle made by reflected ray with the normal at the point of incidence

Angle of reflection is always what to the angle of incidence

image which can be obtained in screen

image which can't be obtained in screen

Change of side of an object and its mirror image is called

It is a mirror whose reflecting surface is the part of hollow sphere of glass

Centre of glass

centre of Spherical mirror

Straight Line passing through centre of curvature and pole is called

Portion of mirror from which the reflection of light actually takes place is called

Focal length

Ratio of the height of image to the height of object is called

Magnification is equals to

If the magnification have plus sign , image is

If the magnification have negative sign then it image is

It is a piece of glass or any other transparent material which is bounded by two triangular surface & three rectangular surface is called

Angle between two refracting faces is called

Angle between incident ray and emergent ray is called

The phenomenon due to which white light splits into seven color is called

The band of seven color obtained on a screen when white light splits into seven color is called

Lens which is thicker in middle and thiner at Edge

Lens which is thin in middle and thicker at Edge

Outer most covering of the eye ball

It is the front bulging part of the eye and allow light to pass in the eye

It is attached to the sclerotic from the inner side and its function is to darken the eye from inside and prevent any internal reflection

The nerve ending from a hemi-spherical screen is called

It receives the optical image of the object and convert it into optical pulse is called

small area facing the eye ball is

It forms a very clear image by sending a large number of optical pulses to brain

It is the region on the retina where the optic nerve enters the eye ball and the image formed on this is not visible

It is a double convex Lens made of transparent tissue

It is a double convex Lens made of transparent tissue held in a position by

It is a circular diaphragm suspenseded in front of the crystalline Lens

The small opening in the iris of an eye is called

whose function is to control the amount of light entering in the eye

It is the jelly like fluid filling the part of eye between crystalline Lens and retina

whose function is to prevent the eye ball from collapsing due to change in atmospheric pressure

It is the filling between cornea and crystalline Lens

whose function is to prevent front of the eye ball from collapsing with change in atmospheric pressure

process by which ciliary muscle alter the focal length of the crystalline Lens so as to focus the nearer or the far off object clearly on the retina

Work equals to

Unit of work

1 joule equal to

Si unit of work

Rate of doing work

power Equal to

power is

unit of power is

Si unit of power is

Si unit of energy

energy is

Energy of a body due to its motion

Kinetic energy equal to

Kinetic energy is

kinetic energy is directly proportional to

If the mass of body is double , its kinetic energy gets

Kinetic energy is directly proportional to

is velocity is double the kinetic energy will be

It is the energy of the body due to its position or change in shape

Potential energy equal to

It is the sum of potential and kinetic energy

The escape velocity for all the object from the earth is

escape velocity from the moon is only what of that from earth

laboratory thermometer measures from

temperature of human body is

Thermometer ranges from

SI unit of heat and energy is

1 calori