Physics (Part-x) (Railway)

The colloidal particles with size (1 nm - 10-⁹m) are enough to scatter a beam of light passing through them.

• This scattering of a beam of light by colloidal particles is  called Tyndall effect.

• They continuously show Tyndall effect because the particles remain suspended in the entire solution.

Electric power is defined as the energy consumed by the electrical appliance per unit time.

• The SI unit of electric power is watt (W).

• It is the power consumed by a device that carries 1 A of current when operated at a potential difference of 1 V.

The presence of magnetic field at a point can be detected by a compass needle.

• In the presence of a magnetic field, the needle of compass rests only in the direction of magnetic field and in the absence of any magnetic, field. the needle of the compass can rest in any direction.

u = 0.6m

f = 0.5

1/f = 1/v + 1/U

⇒ 1/0.5 - 1/0.6 = 1/V

1/0.3 = 1/v

or, v = 3

Magnification (m) = -v/u

= - 30/6 = -5

Refractive index of a medium is defined as the ratio of the velocity of light in air and the velocity of light in that medium.

• Refractive index, μ = c/v, c is the velocity of light in air and v is the velocity of light in the medium.

The series circuit is a closed circuit in which cur-rent flows from one path.

• In this setup, the bulbs are connected in such a way that electricity passes from the source to the first bulb/light and then to the second and so on until it reaches the last bulb and then return to the source.

• This type of connection is used in decorative lighting.

pole to infinity, virtual and erect.

• In a concave mirror, when the object is at infinity, the image is formed at the focus or in the focal plane.

• As the object is moved from the pole towards the focus of a concave mirror, the corresponding image moves from pole to infinity.

• When the object is placed between the focus and the pole, the image will be virtual and hence it will be formed behind the concave mirror.

The current produced during electromagnetic induction is called Induced current.

• The magnitude of the induced current can be increased by moving the magnet more quickly into or out of the coil, using a stronger magnet and increasing the number of turns in the coil.

Current will be induced in a conductor when there is a change of magnetic flux.

• But, if the conductor is moving parallel to magnetic field. magnetic flux will not change and hence, induced current will not be developed.