Alternating Current and Direct Current

Q.

How can you convert a galvanometer into a voltmeter?

Q. A 90 cm long string has fundamental frequency 124 Hz. Where should it be brushed to produce a fundamental frequency of 186 Hz? 1) 60 cm from one end 2) 30 cm from one end 3) 40 cm from one end 4) Both 1 and 2

Q.

Does Concentration affect Electrolysis?

Q.

The essential difference between an AC generator and a DC generator is that

1. AC generator has an electromagnet while a DC generator has a permanent magnet.

2. DC generator will generate a higher voltage.

3. AC generator will generate a higher voltage.

4. AC generator has slip rings while the DC generator has a commutator.

Q.

Which instrument is used for measuring electric potential?

Q. Why is AC attractive in nature and DC repulsive?
AC : Alternating current
DC : Direct current

Q.

A modem is connected between a telephone line and a

1. Network

2. Computer

3. Communication adapter

4. Serial port

Q. In an electric motor why only the brushes made up of carbon are used why not iron, copper etc.?

Q. An ammeter has 20 divisions between 0 and mark 2 on its scale. Find the least count of the ammeter.

Q.

Can AC be used for electrolysis?

Q.

In a DC generator, the induced e.m.f. in the armature is :

1. DC

2. AC

3. Fluctuating DC

4. Can't be said

Q.

The energy conversion taking place in a DC Motor and an AC Generator respectively are:

1. Electric energy into mechanical energy and mechanical energy into electrical energy

2. Electric energy into mechanical energy and heat energy into electrical energy

3. Light energy into mechanical energy and light energy into electrical energy

4. Heat energy into mechanical energy and mechanical energy into electrical energy

Q.

Calculate the frequency of an EM wave with a wavelength of 4000 A⁰.

1. 7.5 x 10¹⁴ Hz

2. 8.5 x 10¹⁴ Hz

3. 4.0 x 10¹⁵ Hz

4. 2.2 x 10¹⁴ Hz

5. 9.5 x 10¹⁵ Hz

Q.

____________ showed that when electricity is passed through the electrolyte solution, a chemical reaction occurs at the electrodes.

Q.

Can resistance value become zero during a short circuit?

Q.

How do you demodulate PAM?

Q.

The current which changes direction after an equal interval of time is known as

Q.

Is the oscilloscope a voltmeter?

Q.

Why high resistance is used in potentiometer?

Q.

Is it better to have a low or high resistance galvanometer?

Q. What are the products of electrolysis of aq. CH3COONa at Pt electrodes?

Q. Why AC shocks are more dangerous than DC shocks?

1. AC current magnitude is huge
2. DC current magnitude is small
3. DC cant find a complete electrical path
4. AC reverses direction periodically causing an attractive force to the body on change of cycles

Q. Why is AC preferred over DC for transmission of electrical power

1. AC to DC conversion and vice versa is very easy
2. AC transmission is unaffected by random phase change
3. Frequency of AC do not change
4. Transmission losses in AC are lower

Q. How does AC differ from DC? What are the advantages and disadvantages of AC over DC?

Q. Alternating current can not be measured by dc ammeter because.

1. Average value of current for complete cycle is zero
2. Ac changes direction
3. Ac can not pass through dc ammeter
4. Dc ammeter will get damaged

Q. Explain the concept of transformers

Q. 2 infinite wires are kept perpendicular to each other without touching each other explain the nature of the force and also mention the motion of wires

Q. For the presence of a current in the circuit we use , and it is always connected with the circuit.

1. galvanometer
2. thermometer
3. in series
4. in parallel

Q.

What is lenz law

Q. Why electric current is a scalar quantity until and unless it has magnitude and direction both?