# Homework Help: Query regarding electrostatics

1. Jun 10, 2010

### KKtm

Hello ppl,
Four equal charges of +10 m C are placed at four corners of a square. The electric intensity at the center of the square is...?
Regards

2. Jun 10, 2010

### KKtm

actually i,ve the following queries, solution for these would be highly appreciated.

(1) Four equal charges of +10 m C are placed at four corners of a square. The electric intensity at the center of the square is:
(a) Zero NC–1
(b) 5 NC–1
(c) 2.5 NC–1
(d) None of these

(2) A current of 200mA is flowing in a conductor. How many electrons are passing
through it in one minute?
(a) 75X1020
(b) 750X1018
(c) 75X1015
(d) None of these

(3) A particle having charge q and moving with velocity v enters in the magnetic field
B at right angles to the field. The force acting on the particle is:
(a) Bqv
(b) Bq/v
(c) Bv/q
(d) None of these

(4) Maximum voltage is induced in the conductor when it moves in the magnetic field
in the direction:
(a) Perpendicular to the field
(b) Parallel to the field
(c) At an angle of 45°to the field
(d) None of these

(5) Lines of magnetic field have the property:
(a) Lines do not terminate at the magnetic poles
(b) Lines continue to pass through the bar magnet
(c) Both (a) and (b)
(d) None of these

(6) Bohr atomic theory cannot explain:
(a) The intensity of spectral lines
(b) Atomic interaction
(c) Both (a) and (b)
(d) None of these

(7) Electron-positron annihilation gives out:
(a) Alpha-rays
(b) Beta-rays
(c) Gamma-rays
(d) None of these

(8) In photoelectric effect the energy of the photon in excess of work function of the
metal is:
(a) Absorbed by the metal
(b) Reflected back
(c) Taken by the emitted electron
(d) None of these

(9) The probability that a particle will leak through a potential barrier is known as:
(a) Tunnel effect
(b) Zeeman effect
(c) Quantum effect
(d) None of these

(10) A narrow wave group helps to determine accurately, the:
(a) Position of a particle
(b) Momentum of a particle
(c) Both (a) and (b)
(d) None of these

(14) Fermions have half integral spin and:
(a) Obey exclusion principle
(b) Do not obey exclusion principle
(c) May or may not obey exclusion principle
(d) None of these

(15) The conversion of atoms of a given element into atoms of a different isotope or of a different element, as in radioactive disintegration or by nuclear bombardment, is
known as:
(b) Transmutation
(c) Transformation
(d) None of these

(16) According to Band theory of solids, free electrons are present in:
(a) Valance band
(b) Conduction band
(c) Both (a) and (b)
(d) None of these

(17) The forbidden energy gap of a material is 0.01eV, the material is:
(a) Semiconductor
(b) Insulator
(c) Conductor
(d) None of these

(20) In a p-n-p transistor, the emitter-base junction is always forward biased while the collector-base junction is reversed biased. As a result, any changes in base current will effect the:
(a) emitter current
(b) base current
(c) collector current
(d) None of these

3. Jun 11, 2010

### Born2bwire

I think you should take these up one at a time in the homework forum.

4. Jun 11, 2010

### KKtm

actually i,ve the following query, solution for this would be highly appreciated.

(1) Four equal charges of +10 m C are placed at four corners of a square. The electric intensity at the center of the square is:
(a) Zero NC–1
(b) 5 NC–1
(c) 2.5 NC–1
(d) None of these

5. Jun 11, 2010

### zzzoak

Please consider the symmetry of the system.

6. Jun 11, 2010

### KKtm

@zzzoak

frd help me in considering, give me the clue kindly

7. Jun 11, 2010

### KKtm

zero...?

8. Jun 11, 2010
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