EEE Sunday, 19 January 2014

Magnetic Circuits Short Mcq Questions Answers

Magnetic Circuits Important Terms

1. Magnetomotive Force (m.m.f): It is magnetic pressure which sets up or tends to set up flux in a magnetic circuit. When electric current is passed through a winding wound  on a core, a magnetic field is produced in the core. The product of current and number of turns of the coil is equal to m.m.f.
m.m.f = N I Ampere-turns (AT)
Adding turns of wire to a coil has the same effect as increasing the current flow. For Example, a one-turn coil with 1 A of current flowing in it produces the same m.m.f as a 10-turn coil with only 0.1 A of current flow. Therefore, effective m.m.f. of a magnetic circuit is equal to the product of the number of turns and current.

Wednesday, 15 January 2014

CAPACITANCE MCQ Short QUESTIONS ANSWERS

CAPACITOR
A capacitor is a device that is capable of storing charge. It essentially consists of two conducting surfaces separated by an insulating material. The conducting surfaces are called plates of the capacitor and the insulating material is called dielectric. The most commonly used dielectrics are air, mica, paper etc.

• A capacitor is generally named after the dielectric used. Example air capacitor, mica capacitor, paper capacitor etc.

• The capacitor may be in the form of parallel plates, concentric cylinders or other arrangement.

Monday, 6 January 2014

Electrostatics MCQ  JOBS STUDY Engineering UNIVERSITY ADMISSION TEST QUESTIONS ANSWERS Part1

• The force between two electrons separated by a distance r varies as  r^-2.
• Two charges are placed at a certain distance apart. A brass sheet is placed between them. The force between them will decrease.
• Study under electrostatics lightning rod.
• The relative permittivity of air is 1 (one).
• The relative permittivity of a material is 10. Its absolute permittivity will be 8.854x10^-11 F/m.
• Another name for relative permittivity is dielectric constant.
• The relative permittivity of most materials lies between 1 and 10.
• When the relative permittivity of the medium is increased, the force between thwo charges placed at a given distance apart decreases.
• Two charges are placed at a distance apart. If a glass slab is placed between them, the force between the charges will decreases.
• A soap bubble is given a negative charge. Its radius Increases.