EASY
Earn 100
Assertion: The resistivity of the semiconductor decreases with increase of temperature.
Reason: In a conducting solid, the rate of collision between free electrons and ions increases with increase of temperature.
31.05% studentsanswered this correctly
Important Questions on Current Electricity
EASY
Two metal wires of identical dimensions are connected in series. If and are the conductivities of the metal wires respectively, the effective conductivity if the combination is:
MEDIUM
The Wheatstone bridge shown in the figure below, gets balanced when the carbon resistor used as has the colour code (orange, red, brown). The resistors and are and , respectively. Assuming that the colour code for the carbon resistors gives their accurate values, the colour code for the carbon resistor, used as , would be
MEDIUM
A carbon resistance has the following colour code. What is the value of the resistance?
EASY
Brown, Red and Orange coloured bands on a Carbon resistor are followed by silver band. The value of resistor is ________.
EASY
Two copper wires of length and have radii and respectively. The ratio of their specific resistances is.
EASY
The electrical conductivity of a metal is
MEDIUM
A carbon resistor is color coded with green, black, red and silver respectively. The maximum current which can be passed through this resistor is:
EASY
A uniform wire of length and radius has a resistance of . It is recast into a wire of radius . The resistance of new wire will be-
EASY
If the valence electrons exactly fill one or more bands, leaving other empty, then the crystal will be
EASY
Wire bound resistors are made by
HARD
A solar cell is to be fabricated for efficient conversion of solar radiation to emf using material The solar cell is to be mechanically protected with the help of a coating using material If the band gap energy of materials and are and respectively, then which of the following choices is optimum for better performance of the solar cell.
EASY
The -side of the depletion layer of a junction
EASY
A wire made of aluminium having resistivity with a circular cross-section and has a radius of . A current of flows through the wire. If the voltage difference between the ends is , the length of the wire in is
MEDIUM
The difference between the maximum and minimum values of resistance of a resistor with the color scheme green-green-red-silver is
MEDIUM
Consider a cylindrical conductor of length and area of cross-section . The specific conductivity varies as where is the distance along the axis of the cylinder from one of its ends. The resistance of the system along the cylindrical axis is
EASY
A wire of resistance is bent to form a complete circle of radius . The resistance between its two diametrically opposite points, and as shown in the figure is
EASY
The resistance of a wire is ohm. If it is melted and stretched to times its original length, its new resistance will be
EASY
Resistance of a carbon resistor determined from colour codes is () . The colour of the third band must be :
MEDIUM
When light shines on a junction diode, the current versus voltage is observed as in figure below.
In which quadrant(s) does the diode generate power, so that it can be used as a solar cell?
EASY
Consider four conducing materials copper, tungsten, mercury and aluminum with resistivity and respectively. Then :
