Current of 4.8 amperes is flowing through a conductor. The number of electrons per second will be [CPMT 1986]
When the current i is flowing through a conductor, the drift velocity is v. If 2i current is flowed through the same metal but having double the area of cross-section, then the drift velocity will be
When current flows through a conductor, then the order of drift velocity of electrons will be [CPMT 1986]
Order of drift velocity
Every atom makes one free electron in copper. If 1.1 ampere current is flowing in the wire of copper having 1 mm diameter, then the drift velocity (approx.) will be (Density of copper =9×103kgm-3 and atomic weight = 63) [CPMT 1989]
Which one is not the correct statement [NCERT 1978]
Because 1 H.P. = 746 J/s = 746 watt
If a 0.1 % increase in length due to stretching, the percentage increase in its resistance will be [MNR 1990; MP PMT 1996; UPSEAT 1999; MP PMT 2000]
The resistivity of iron is1×10-7ohm−m. The resistance of a iron wire of particular length and thickness is 1 ohm. If the length and the diameter of wire both are doubled, then the resistivity in ohm−m will be [CPMT 1983; DPMT 1999]
Because it is an intensive property
The temperature coefficient of resistance for a wire is 0.00125/∘C. At 300K its resistance is 1 ohm. The temperature at which the resistance becomes 2 ohm is [IIT 1980; MP PET 2002; KCET 2003; MP PMT 2001; Orissa JEE 2002]
The battery E has an e.m.f.of 2volt If the galvanometer Greads zero, then the value of the resistance X in ohm is [NCERT 1990; AIEEE 2005]
The magnitude and direction of the current in the circuit shown will be [CPMT 1986, 88]
A cell of e.m.f. 1.5V having a finite internal resistance is connected to a load resistance of 2Ω. For maximum power transfer the internal resistance of the cell should be [BIT 1988]
For maximum power, external resistance = internal resistance.
By a cell a current of 0.9 A flows through 2 ohm resistor and 0.3 A through 7 ohm resistor. The internal resistance of the cell is [KCET 2003]
The e.m.f. of a cell is E volts and internal resistance is r ohm. The resistance in external circuit is alsor ohm. The p.d. across the cell will be [CPMT 1985; NCERT 1973]
Since both the resistors are same, therefore potential difference
Two cells, e.m.f. of each is E and internal resistance r are connected in parallel between the resistance R. The maximum energy given to the resistor will be, only when [MNR 1988; MP PET 2000; UPSEAT 2001]
We know that when two equal resistors are connected in parallel the equivalent resistance becomes half.
Also maximum power is delivered when load resistance = equivalent internal resistance.
Hence A is correct.
Kirchhoff's first law i.e. Σi=0 at a junction is based on the law of conservation of [CBSE PMT 1997; AIIMS 2000; MP PMT 2002; RPMT 2001; DPMT 2005]