Direction of magnetic field due to a current carrying conductor
“How do we know the direction of magnetic field around the current carrying conductor?” Asked Nikhil Incoming search terms:direction of magnetic field around a current carrying conductorDIRECTION OF MAGNETIC FIELD IN CURRENT CARRYING CONDUCTORmagne...
Categories: Ask Physics, Current Electricity, Electromagnetism, Magnetism, Project Tags: carrying, conductor, conductorDIRECTION, current, direction, electric current, field, fieldLink, magnet, magnetic effect, magnetic field, Physics, post, search terms
Electrons and flow of electrons – Did you have this doubt before?
“When an electric cell is connected to a circuit, electrons flow away from the negative terminal in the circuit. But within the cell, electrons flow to the negative terminal. Explain? Answer: The question seems to be the result of some misconceptions. If we consider an electrochemical cell, it is the chemical reactions which develops and ...Read the full post
Categories: Ask Physics, conduction, Current Electricity, ELECTROSTATICS, General, Interesting Questions Tags: electron, emf
Change in resistance due to stretching a wire
“There is a wire whose resistance is R. it is streched, and its length gets increased to 2%. find new resistance.” – Knishka Agrawal asked Answer: The resistivity does not change due to stretching, but the length and area of cross section changes; but the volume remains constant. Therefore, resistance changes which can be calculated ...Read the full post
Categories: Ask Physics, change in resistance, Current Electricity, stretching Tags: resistance, resistivity
What is meant by charge on a capacitor?
Mohit asked this question:
“What is meant by charge on a capacitor?”
Answer: As we know, a simple capacitor (say a parallel plate capacitor) 
consists of two plates parallel to each other. When charged, charge on either plate of the capacitor is called charge on the capacitor.
The following links will help you explore further and understand more
- http://www.kpsec.freeuk.com/components/capac.htm
- http://hyperphysics.phy-astr.gsu.edu/hbase/electric/capac.html
- http://www.youtube.com/watch?v=zNpbdptwxlQ
- http://www.youtube.com/watch?v=qdXbnhb1bVo&feature=related
Categories: Answers, CBSE, Current Electricity, ELECTROSTATICS, Electrostatics, Entrance Exams Tags: capacitance, capacitor, charge on a capacitor, principle of a capacitor
DERIVATION OF CELLS IN SERIES AND PARALLEL
jaipreet singh asked: “can you please tell me the DERIVATION OF CELLS IN SERIES AND PARALLEL?”
Answer: I am posting here the simplified treatment to calculate the current in a circuit with combination of cells.
In this derivation it is assumed that all cells have the same EMF and same internal resistance.
CELLS IN SERIES
Consider n identical cells of emf E and internal resistance r connected in series across an external resistor of resistance R.
The total internal resistance = nr (since the internal resistances come in series)
The total resistance in the circuit = nr+R
The total emf = nE (since the emfs add up in series circuit)
Therefore, the current in the circuit;
PARALLEL COMBINATION OF CELLS
Consider m identical cells of emf E and internal resistance connected in parallel across an external resistor of resistance R.
The total emf in circuit = E (Since each cell has the same emf and they are in parallel)
The net internal resistance = r/m (since the cells are in parallel, their resistances are also in parallel. If m identical resistances are in parallel, the effective resistance is r/m)
The total resistance in circuit = R + r/m
Therefore, the current in circuit;
MIXED COMBINATION OF CELLS
Consider a combination of m rows of n cells each. The emf of each cell is E and the internal resistance of each cell is r. This combination is connected across and external resistance R.
The total EMF = nE
The net internal resistance = nr/m
The total resistance in circuit = R + nr/m
The current in circuit;
Categories: Current Electricity Tags: answer, cell, combination of cells, derivation, emfs, external resistor, internal resistance, parallel combination, singh, treatment
