In a conductor , if the number of conduction electron per unit volume is and mean free time is ( femto second ) , it's approximate resistivity is :
Space between two concentric conducting spheres of radii a and b (b>a) is filled with a medium of resistivity . The resistance between the two spheres will be :
In an experiment , the resistance of a material is plotted as a function of temperature (in some range).
As shown in the figure, it is a staright line.
One may conclude that:
Which of the following combinations has the dimension of electrical resistance ( is the permittivity of vacuum and is the permeability of vacuum) ?
The resistive network shown below is connected to a D.C. source of 16 V. The power consumed by the network is 4 Watt. The value of R is :
A galvanometer of resistance has 50 divisions on its scale and has sensitivity of division. It is to be converted to a voltmeter with three ranges, of , and . The appropriate circuit to do so is :
A current of 5 A passes through a copper conductor ( Resistivity = )
of radius of cross-section 5mm. Find the mobility of the charges if their drift velocity is .
In the given meter bridge experiment,the circuit diagram
and the corresponding observation table are shown in fig.
Which of the reading is inconsistent?
In the given circuit , an ideal voltmeter connected across the
resistance reads 2V. The internal resistance r , of each cell is :
A moving coil galvanometer allows a full scale current of A. A series resistance of 200 is required to convert the above galvanometer into an voltmeter of range0-5 V . Therefore the value of shunt resistance required to convert the above galvanometer into an ammeter of range0-10 mA is :
A moving coil galvanometer, having a resistance G, produces full-scale deflection when a current flows through it. This galvanometer can be converted into (i) an ammeter of range 0 to by connecting a shunt resistance to it and (ii) into a voltmeter of range 0 to by connecting a series resistance to it. Then,
One kg of water, at , is heated in an electric kettle whose heating element has a mean (temperature averaged) resistance of . The rms voltage in the mains is 200 V. Ignoring heat loss from the kettle, time taken for water to evaporate fully, is close to :
[ Specific heat of water =, Latent heat of water = 2260 kJ/kg]
In the figure shown, what is the current (in ampere) drawn from the battery? you are given:
A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when:
In the circuit shown, a four-wire potentiometer is made of a 400 cm long wire, which extends between A and B. The resistance per unit length of the potentiometer wire is . if an ideal voltmeter is connected as shown with jockey J at 50 cm from end A, the expected reading of the voltlmeter will be:
The resistance of a galvanometer is and the maximum current which can be passed through it is . What resistance must be connected to it in order to convert it into an ammeter of range ?
A metal wire of resistance is elongated to make a uniform wire of double its previous length . This new wire is now bent and the ends joined to make a circle . If two points on this circle make an angle at the centre , the equivalent resistance between these two points will be :
A moving coil galvanometer has resistance and it indicates full deflaction at current. A voltmeter is made using this galvanometer and a resistance. The maximum voltage , that can be measured using this voltmeter,will be close to :
A wire of resistance is bent to form a square as shown in the figure. The effective resistance between and is :( is mid-point of arm CD)
For the circuit shown, with and the potential difference between the points 'a' and 'b' is approximately(in V) :