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Answered on 09 Feb CBSE/Class 12/Science/Physics CBSE/Class 11/Science/Physics

A source of 100cP is suspended 6m varticaly about a point P on a horizantal surface.1.find illumination... read more

A source of 100cP is suspended 6m varticaly about a point P on a horizantal surface.1.find illumination at point P.

1.illumination at P.

I=l/R^2

=100/6^2

=2.7 lumen/m^2

Mohan Gangul

Tutor

1
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Answered on 02 Feb CBSE/Class 12/Science/Physics Tuition/Class XI-XII Tuition (PUC)

Name the phenomenon which shows the quantum nature of electromagnetic radiation.

Bhojraj Sharma

Tutor

Photoelectric effect
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Answered on 05 Mar CBSE/Class 12/Science/Physics Tuition/Class XI-XII Tuition (PUC)

Write the principle of working of a metre bridge.

Physics Teacher

wheatstone bridge principle. here p/q=r/s.p=unknown resistance,q=resistance of the resistance box given to the circuit.if l=length of the slide wire at which when tip of the jockey touches it gives zero deflection in the galvanometer,then r=l and s=100-l. so p=q(l/100-l). read more

wheatstone bridge principle.

here p/q=r/s.p=unknown resistance,q=resistance of the resistance box given to the circuit.if l=length of the slide wire at which when tip of the jockey touches it gives zero deflection in the galvanometer,then r=l and s=100-l.

so p=q$imes$(l/100-l).

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Answered on 22 Feb CBSE/Class 12/Science/Physics Tuition/Class XI-XII Tuition (PUC)

Write the functions of the three segments of a transistor.

Diksha Marwaha

Tutor

Transistor consist of emitter,collector and base.each one is having a particular function . 1.)emitter emits the charge carriers . 2.)collector collects the charge carriers . 3)base provides interaction between emitter and. Collector.
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Answered on 01 Mar CBSE/Class 12/Science/Physics Tuition/Class XI-XII Tuition (PUC)

State the condition under which a large magnification can be achieved in an astronomical telescope.

D Mukherjee

Teacher

There is large magnification when the image formed by the objective is within the focal length of the eye pece of the telescope
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Answered on 23 Feb CBSE/Class 12/Science/Physics Tuition/Class XI-XII Tuition (PUC)

Electrons are emitted from the cathode of a photocell of negligible work function, when photons of wavelength... read more
Electrons are emitted from the cathode of a photocell of negligible work function, when photons of wavelength are incident on it. Derive the expression for the de Broglie wavelength of the electrons emitted in terms of the wavelength of the incident light. read less

Ramya

Primary Teacher

E=Φ+K.E max. Where: Φ=work function of electrode Given: Φ=0 ∴ E=K.E of electron where: E= incident energy. λ=h÷p. Where: h= plank cons. P= momentum K.E = (1÷2)mv* *=2 p= mv ∴ p=√2mK.E. Now put value in de- Broglie wavelength formula we... read more

E=Φ+K.E max.

Where: Φ=work function of electrode

Given: Φ=0

∴ E=K.E of electron where: E= incident energy.

λ=h÷p.

Where: h= plank cons.

P= momentum

K.E = (1÷2)mv*    *=2

p= mv

∴ p=√2mK.E.

Now put value in de- Broglie wavelength formula we get,

λ = h÷√2mK.E required and.

Where:λ= de Broglie wavelength

K.E= kinetic energy of electron.

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Answered on 19 Feb CBSE/Class 12/Science/Physics Tuition/Class XI-XII Tuition (PUC)

Draw the pattern of magnetic field lines for a circular coil carrying current.

Diksha Marwaha

Tutor

A pair of conducting circular coils each having N turns, each carrying a current I, separated by a distance equivalent to the radius of the circular loops, produce a homogeneous magnetic field B in the mid-plane between the two circular coils. a = radius of the coilsa = separation between... read more

 A pair of conducting circular coils each having N turns, each carrying a current I, separated by a distance equivalent to the radius of the circular loops, produce a homogeneous magnetic field B in the mid-plane between the two circular coils. a = radius of the coilsa = separation between the coilsa/2 = distance to the mid-planeB = magnetic field at the mid-plane
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Answered on 18 Feb CBSE/Class 12/Science/Physics Tuition/Class XI-XII Tuition (PUC)

State Lenzâ??s law. Explain, by giving examples that Lenzâ??s law is a consequence of conservation of energy.

Ramya

Primary Teacher

Lenz's Law states that, when you induce a current in a wire via a changing magnetic field, the current flows through the wire in such a direction so that its magnetic field opposes the change that produced the current. So, what happens when you induce a current by, say, moving a wire through a magnetic... read more

Lenz's Law states that, when you induce a current in a wire via a changing magnetic field, the current flows through the wire in such a direction so that its magnetic field opposes the change that produced the current.

So, what happens when you induce a current by, say, moving a wire through a magnetic field, is that you're converting mechanical energy (the energy of the wire's motion) into electrical energy (the energy carried by the induced current).

Lenz's Law ensures that the mechanical energy of the wire is reduced by the same amount of energy gained by the current. It does this by exerting a force on the wire opposing the wire's motion. This causes the wire to lose mechanical energy (its motion is impeded); it must do work against the induced magnetic field to generate current.

To make this a little more concrete, let's imagine a fictitious universe where Lenz's Law doesn't apply; i.e. a universe in which

there's no force generated on the wire at all, despite the induced current.

In this fictitious universe, imagine that you give the wire one unit of mechanical energy. As the wire passes through a magnetic field, a current appears in the wire that also carries one unit of energy. But since no opposing force is generated, no mechanical energy is lost; the wire still has its original one unit of mechanical energy. Which means that the wire now has two units of total energy (one electrical; one mechanical). You've created energy from nothing!

In the real universe, Lenz's Law ensures that, if the electrical energy gained is one unit then the mechanical energy lost is also one unit, so that the net energy gain of the wire is zero. Energy is conserved.

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Answered on 05 Mar CBSE/Class 12/Science/Physics

Do electromagnetic waves carry energy and momentum?

Ramya

Primary Teacher

An electromagnetic wave, although it carries no mass, does carry energy. It also has momentum, and can exert pressure (known as radiation pressure). The reason tails of comets point away from the Sun is the radiation pressure exerted on the tail by the light (and other forms of radiation) from sun
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Answered on 18 Feb CBSE/Class 12/Science/Physics

Draw logic symbol of an OR gate and write its truth table.

Ramya

Primary Teacher

OR gate The OR gate is an electronic circuit that gives a high output (1) if one or more of its inputs are high. A plus (+) is used to show the OR operation. read more
OR gate
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The OR gate is an electronic circuit that gives a high output (1) if one or more of its inputs are high.  A plus (+) is used to show the OR operation.
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