DC Circuit-short Question and Answer

 TOPIC- DC Circuit -Short Question and Answer

Q.1.Why are domestic appliances connected in parallel?

Ans.The domestic appliances are connected in parallel due to the following reasons:

(i)The domestic appliance are rated for the same voltage (i.e.,230V) but different power. When

connected in parallel,the performance of each appliance become independent of the other.Thus a 230V, 250W TV receiver can be operated independently in parallel with a 230V,100W lamp.

(ii)If a break occurs in any one of the branch circuits,it will have no effect on the other branch circuit.

Q.2.Why does a cell posses internal resistance?

Ans.When current flows through a cell, it meets opposition from the electrodes and the electrolyte.

This opposition to current offered by the cell is called its internal resistance.

Basic Electrical - Short Question and Answer

TOPIC : Basic Electrical Short Question and Answer 

Q.1.Why does a positive charge attract a negative charge ?

Ans. It is the tendency of every body to have minimum electric potential i.e., to obtain zero potential. A positive charge means deficit of electrons while the negative charge indicates excess of electrons. Consequently, positive and negative charges attract each other to have minimum electric potential.  

Q.2. A wire is carrying current. Is it charged?

Ans. No. The current in a wire is due to the drifting of free electrons in a definite direction. But the number of electrons in the wire at any instant is equal to the number of protons. Hence, the net charge on the wire is zero.

Electrical Illumination Fill In The Blanks

 FILL IN THE BLANKS

1. Visible light has wavelength between 4000 A and 7500 A.

2. Human eye is most sensitive for a wave length of 5500.

3. The color corresponding to wavelength 5500 A is Yellow, Green. 

4. Lamp efficiency is expressed in Lumens per watt.

Electric Illumination are true (T) or false (F)

TRUE AND FALSE

1. Carbon arc lamps needs frequent adjustment and replacement of carbon rod.--T

2. Lumen method takes into account the inter-reflections of light inside a room.--T

3. Luminairs are generally categorized as industrial, commercial or residential.--T

4. Lenses with prismatic patterns refract light sources to disperse the rays or to direct them most effectively.--T

Multiple Choice Questions of Electric Illumination

MCQ of Illumination

1. Radiant efficiency of the luminous source depends on
(A) shape of the source
(B) temperature of the source
(C) wavelength of light rays
(D) all of the above.

2. Light waves travel with a velocity of
(A) 3 x 10¹⁰cm/s
(B) 3 x 10¹²cm/s
(C) 3 x 10¹⁵ cm/s
(D) 3 x 10¹⁸ cm/s

Illumination Engineering

Electrical Illumination Definitions

Light

it is defined as the radiant energy from a hot body which produce the visual sensation upon human eye. It is usually denoted by Q, expressed in lumen-hours and is analogous to watt-hours.

Luminous Flux(F or Ф)

It is defined as the total quantity of light energy per second from a luminous body.It is represented by symbol F or Ф and unit is lumen.

Approximate relation between lumen and electric unit of power i.e. watt is given as

 1lumen=0.0016 watt(approx).

MCB or Miniature Circuit Breaker

What is MCB?

 it is device which protect conductor or electrical installation from short circuit or overload. Now-a-day instead of fusethey are used both residential and industrical wiring.These can be single pole, double pole or triple pole. It sustained overloading of 150% or above.