Transistors

Q.

What are the limitations of ohm’s law.

Q.

What are non-ohmic resistance? Give two examples.

Q.

What do you understand by the term electric conductance? State its practical unit.

Q.

How much current will an electric bulb draw from a $220V$ source, if the resistance of the filament of the bulb is $1100\Omega$?

Q.

Which component has the biggest size in the transistor?

1. Collector

2. Base

3. Emitter

4. Switch

Q.

What are ohmic resistance? Give two examples?

Q.

How many pn junctions does a transistor have?

1. 1

2. 2

3. 4

4. 8

Q.

Memory is made up of

1. Large number of cells

2. Set of wires

3. Set of circuits

4. None of the above

Q.

Name two materials in each case whose resistance (c) decreases with the rise in temperature

Q. 4.In the circuit shown in figure, the battery is an ideal one with emf V. The capacitor is initially uncharged. The switch S is closed at time t =0. (a) Find the charge Q on the capacitor at time t. (b) Find the current in AB at time t. What is its limiting value as t tends to infinity?

Q.

Name the metals which are generally used for making electrical transmission lines.

Q.

Is the photodiode active or passive?

Q. Under forward bias, an ideal p-n junction diode will act as a perfect insulator.

1. 200
2. 100

Q.

A diode as a rectifier converts?

Q.

How many terminals does a transistor have?

1. 2

2. 4

3. 3

4. 5

Q.

Name a metal which offers higher resistance to the passage of electricity than copper.

Q.

Name the properties for which Aluminium is used in overhead electrical transmission conductor.

Q.

Which of the following is non-ohmic resistance?

1. Copper wire

2. Brass wire

3. Copper wire wound on an electromagnet

4. Constantan wire

Q.

State the factors on which the internal resistance of a cell depends.

Q.

In the verification of Ohms law, what is observed when the ratio of potential difference and current $(V/I)$ is calculated for all the readings? What do you conclude?

Q.

Why is tungsten used to make the filament of electric bulbs? Give any three reasons.

Q.

The electrical resistivity of few materials is given below in ohm-metre. Which of these material can be used for making element of heating device?

A) $6.84\times {10}^{-8}$

B) $1.60\times {10}^{-8}$

C) $1.00\times {10}^{-4}$

D) $2.50\times {10}^{12}$

E) $4.40\times {10}^{-5}$

F) $2.30\times {10}^{17}$

Q.

When 2V is the potential difference across a conductor the current in the conductor is 0.4 ampere. What is the resistance of the conductor?

Q.

Name two materials in each case whose resistance

(a) increases

with the rise in the temperature.

Q.

Why do we need combinations of resistances (or resistors) in electrical circuits?

Q. Which of the following is a three terminal device?

1. LED
2. Photo diode
3. Transistor
4. None of these

Q.

A torch bulb is rated $5V$ and $500mA$.

Calculate its b. resistance

Q.

Should the heating element of an electric iron be made of iron, silver, or nichrome?

Q.

Which of the following an ohmic resistance?

1. Diode valve

2. Filament of a bulb

3. Carbon are light

4. Manganin wire

Q.

Substances having moderate resistivity are called ___ and used for making ___.