A Wheatstone bridge is shown in figure. Name a practical device which uses this principle.

In the given question we have to use the concept of a practical device which uses wheatstone bridge principle and apply it to solve the given question.a practical device which uses this principle. Meter bridge a practical device which uses wheatstone bridge principle. Hence, Meter bridge will be the correct answer of the given question.

How will you represent a resistance of 3700 Ω ± 5 % using colour code ?

The value of carbon resistance 3700 Ω ± 5 % is 3 . 7 × 10 2 ± 5 % The colour assigned fo r number 3.7 and 2 are violet and red respectively. For ± 5 % accuracy, the colour is gold. Thus, the bands of colour on carbon resistor in sequence are orange, violet red and gold.

The transfer characteristic of n - p - n - transistor in CE - configuration is shown in the figure. Find the cut-off region, active region and saturation region from it.

Cut off region :- Cutoff mode is the opposite of saturation.A transistor in cutoff mode is off - there is no collector current, and therefore no emitter current. It almost looks like an open circuit. To get a transistor into cutoff mode, the base voltage must be less than both the emitter and collector voltages. Saturation region :- The point where the load line intersects the I B = I B ( sat ) curve is called saturation.At this point, the base current is maximum and so is the collector current. At saturation, collector-base junction no longer remains reverse biased and normal transistor action is lost. Active region :- The region between cut off and saturation is known as active region.In the active region, collector-base junction remains reverse biased while base-emitter junction remains forward biased. Consequently, the transistor will function normally in this region. Here, the region are given as below, I - cut off region II - active region III - saturation region

The transfer characteristic of n - p - n - transistor in CE - configuration is shown in the figure. In which of these regions, a transistor is said to be switched off.

Cut off region :- Cutoff mode is the opposite of saturation.A transistor in cutoff mode is off - there is no collector current, and therefore no emitter current. It almost looks like an open circuit. To get a transistor into cutoff mode, the base voltage must be less than both the emitter and collector voltages. Saturation region :- The point where the load line intersects the I B = I B ( sat ) curve is called saturation.At this point, the base current is maximum and so is the collector current. At saturation, collector-base junction no longer remains reverse biased and normal transistor action is lost. Active region :- The region between cut off and saturation is known as active region.In the active region, collector-base junction remains reverse biased while base-emitter junction remains forward biased. Consequently, the transistor will function normally in this region. In region - I , the transistor is said to be switched off. Hence, region - I , is the required answer.

The transfer characteristic of n - p - n , transistor in CE - configuration is shown in the figure. In the working of a transistor, the emitter-base ( EB ) - junction is forward biased while collector base ( CB ) - junction is reverse biased. Why ?

This bias system is the condition of the transistor to be active. As the emitter-base is forward biased the input resistance i.e the resistance of the emitter-base junction becomes very small. Again as the collector base junction is reverse biased the output resistance i.e the resistance of the emitter-collector becomes very high. The circuit with low input resistance and high output resistance acts as the best amplifier. That is why the emitter-base junction is forward biased while collector-base junction is reversed biased.

The experimental set up to find an unknown resistance using a metre bridge is shown below: If the galvanometer and cell are interchanged at the balance point of the bridge, would the galvanometer show any current?

A galvanometer is a device that detects or measures the magnitude of a tiny electric current. The movement of a magnetic needle or a coil in a magnetic field, which is an integral part of a galvanometer, is commonly used to indicate the current and its strength. Now, If the galvanometer and cell are interchanged at the balance point of the bridge.The balance point remains unaltered if the galvanometer and the cell are swapped. As a result, the galvanometer will display no current and the deflection will be zero.

The experimental set up to find an unknown resistance using a metre bridge is shown below: b If the balance point is found to be at 39 . 5 cm from the end A , the resistor S is of 12 . 5 Ω . Determine the resistance R . Why are the connections between resistors in a metre bridge made of thick copper strips?

Condition for balanced wheatstone bridge, X Y = 100 − l 1 l 1 Y = 12 . 5 Ω I 1 = 39 . 5 c m X = 8 . 2 Ω To minimize the resistance which is not taken into formula.

The experimental set up to find an unknown resistance using a metre bridge is shown below: a What is the working principle for a metre bridge?

The principle of working of Metre bridge is wheat stone bridge principle and it is used to find the resistance of an unknown conductor or to compare two unknown resistance.

The temperature dependence of resistivity of a material is shown below: b Write the relation between resistivity and average collision time for electron.

The average of velocities of all electrons just after collisions is 0, as they get bounced in all random directions. Hence, the average velocity of an electron along the length of a resistor or conductor wire is equal to that gained due to electrostatic field E. So the required relation is v = eJρτ m ⇒ τ = mv eJρ .

The temperature dependence of resistivity of a material is shown below: Identify the type of material.

In a semiconductor when temperature increases conductivity increases so resistivity decreases i.e. T ∝ ρ 1 ρT = constant ⇒ ρ = K 1 T dρ = − K 1 T 2 dT ⇒ dT dρ = − K T 2 So, slope of ρ−T curve is negative & it is dependent upon T i.e. it is not constant. Hence, the required material is semiconductor.

Write the unit of mobility.

The mobility is given as value of drift velocity per unit of the electric field strength. μ = V d E The unit of the mobility is m 2 V . s

The transfer characteristic of n - p - n , transistor in CE - configuration is shown in the figure. In the working of a transistor, the emitter-base ( EB ) - junction is forward biased while collector base ( CB ) - junction is reverse biased. Why ?

This bias system is the condition of the transistor to be active. As the emitter-base is forward biased the input resistance i.e the resistance of the emitter-base junction becomes very small. Again as the collector base junction is reverse biased the output resistance i.e the resistance of the emitter-collector becomes very high. The circuit with low input resistance and high output resistance acts as the best amplifier. That is why the emitter-base junction is forward biased while collector-base junction is reversed biased.

E M B I B E

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 3 - Current Electricity>Kerala Board-2020>Q 15

MEDIUM

12th Kerala Board

IMPORTANT

Earn 100

A Wheatstone bridge is shown in figure.

Derive a relation connecting the four resistors for the galvanometer to give zero or null defection.

Important Questions on Current Electricity

MEDIUM

12th Kerala Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 3 - Current Electricity>Kerala Board-2020>Q 16

A Wheatstone bridge is shown in figure.

Question Image

Name a practical device which uses this principle.

EASY

12th Kerala Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 3 - Current Electricity>Kerala Board-2018>Q 17

How will you represent a resistance of

3700 Ω \pm 5 %

using colour code ?

HARD

12th Kerala Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 3 - Current Electricity>Kerala Board-2020>Q 18

The transfer characteristic of $n - p - n$ - transistor in $CE$ - configuration is shown in the figure.

Question Image

Find the cut-off region, active region and saturation region from it.

EASY

12th Kerala Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 3 - Current Electricity>Kerala Board-2020>Q 19

The transfer characteristic of $n - p - n$ - transistor in $CE$ - configuration is shown in the figure.

Question Image

In which of these regions, a transistor is said to be switched off.

HARD

12th Kerala Board

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 3 - Current Electricity>Kerala Board-2020>Q 20

The transfer characteristic of $n - p - n$ - transistor in $CE$ - configuration is shown in the figure.

Question Image

A $CE$ - transistor amplifier is shown in figure.

Question Image

In this, the audio signal voltage across collector resistance of $2.0 KΩ$ is $2.0 V$ . Suppose the current amplification factor of the transistor is $100$ . Then calculate the value of signal current through the base.