List of top Physics Questions on Electrical Instruments

Consider the correct statements in respect of the thermoelectric instruments. The correct sequence is:
A. They indicate the rms value of current or voltage
B. They suffer from waveforms errors
C. They can be used for frequency range of the order of MHz
D. They have a low overload capacity
E. They have a high accuracy
Choose the correct answer from the options given below:

When a metal conductor is connected to left gap of meter bridge is heated, the balancing point

A galvanometer of resistance 50 Ω is connected to the battery of 3 V along with a resistance 2950 Ω in series. A full scale deflections of 30 divisions is obtained in galvanometer. In order to reduce this deflections to 20 division, the resistance in series should be

If only $\frac{1}{51}^{th}$ ot the main current is to be passed through a galvanometer then the shunt required is $R_1$ and if only $\frac{1}{11}^{th}$ of the main voltage is to be developed across the galvanometer, then the resistance required is $R_2$. Then $\frac{R_2}{R_1} =$

The AC voltage across a resistance can be measured using a :

A galvanometer with a scale divided into $100$ equal divisions has a current sensitivity of $10$ divisions per milliampere and a voltage sensitivity of $2$ divisions per millivolt. The galvanometer resistance will be

The net resistance of an ammeter should be small to ensure that

An ammeter reads upto $1A$. Its internal resistance is $0.81\, \Omega$ . To increase the range to $10\, A$, the value of the required shunt is

The current in the primary circuit of a potentiometer is $0.2\, A$. The specific resistance and cross-section of the potentiometer wire are $4 ??10^{-7}$ ohm metre and $8 ??10^{-7} \, m^2$ respectively. The potential gradient will be equal to :

Pyrometer is an instrument used to measure

Two tangent galvanometer having coils of the same radius are connected in series. A current flowing in them produces deflection of $60^{\circ}$ and $45^{\circ}$ respectively. The ratio of the number of turns in the coils is

When a galvanometer is shunted by resistance S, its current capacity increases n times. If the same galvanometer is shunted by another resistance S', its current capacity will increase by n' is given by

A galvanometer of resistance $ 50\,\Omega $ is connected to a battery of $ 3 \,V $ along with a resistance of $ 2950\,\Omega $ in series. A full scale deflection of $ 30 $ divisions is obtained in the galvanometer. In order to reduce this deflection to $ 20 $ divisions, the resistance in series should be

A galvanometer acting as a voltmeter will have

In a potentiometer the null point is obtained at $7^\text{th}$ wire. If now we have to change the null point at $9^\text{th}$ wire, what should we do?

In a tangent galvanometer, a current of 1A produces a deflection of 30?. The current required to produce a deflection of 60? is

A moving coil galvanometer has a resistance of $ 10\, O $ and full scale deflection of $ 0.01\, A $ . It can be converted into voltmeter of $ 10\, V $ full scale by connecting into resistance of :

To send 10% of main current through a moving coil galvanometer of resistance $99\,\Omega$ the shunt required is

Tangent galvanometer is used to measure

To increase the range of a voltmeter

When the temperature exceeds the transition temperature, a ferromagnetic material becomes similar to:

Narrow capillary tubes A and B are of length l and l/2 and of the same radius r. The rate of flow of water through the tube A under a constant pressure head 'P' is 3 cm³/sec. If A and B are connected in series and the same pressure difference 'P' is maintained between the ends of the composite tube, then the rate of flow of water is

The coil of the ballistic galvanometer oscillates due to :

A battery of e.m.f. 12V and internal resistance $2\Omega$ is connected in series with a tangent galvanometer of resistance $4\Omega$. The deflection is $60^\circ$ when the plane of the coil is along the magnetic meridian. To get a deflection of $30^\circ$, the resistance to be connected in series with the tangent galvanometer is :