Physics Test - 21

The output of a NOR gate is high if all inputs are low.

The NAND and NOR gates are universal gates. A universal gate is a gate which can implement any Boolean function without need to use any other gate type. That means we can implement any logic function using NAND and NOR gates without need of AND, OR or NOT gates.

• NOR gate is formed by connecting a NOT gate at the output of OR gate.
• NAND gate is formed by connecting NOT gate the output of AND gate.

Threshold frequency for metal surface corresponds to an energy \((\nu)=6.2 {eV}\)

Stopping potential for the radiation incident on it is \((V_{0})=5 {~V}\)

We know that in the photoelectric experiment

\(E=W+K\)

\(h \nu=h \nu_{o}+e V_{o}\)

Put the given values in above equation,

\(h \nu=6.2 e V+5 e V=11.2 e V\)

We know that,

\(h \nu=\frac{h c}{\lambda}\)

\(\Rightarrow\frac{h c}{\lambda}=11.2 e V\)

\(\Rightarrow c=3×10^{8}m/s\)

\(\Rightarrow\frac{1242 e V~ n m}{\lambda}=11.2 e V\)

\(\Rightarrow\lambda=\frac{1242 e V~ n m}{11.2 e V}=110.89~ n m \simeq 1100 A^{\circ}\)

Which is under the ultraviolet region.

Under the static condition, the electric field inside the solid perfect conductor is zero in electrostatic equilibrium even if:

• It is isolated.
• It is charged.
• It is present in the external electrostatic field.

Now, it is known that a perfect solid conductor is an equipotential body. The potential inside the conductor is the same as the potential at the surface.

Since the surface of the solid conductor is an equipotential surface, therefore, the electric field will be perpendicular or in other words normal to the perfectly solid conductor surface.

When light scattered by a molecule and the frequency of the scattered light is changed, this phenomenon is calledRaman effect.

• The Raman Effect is the phenomenon of scattering of light by molecules present in a medium.​
• When a beam of light travels through a transparent object, a small fraction of the light gets scattered in directions other than where it should.
• The scattering occurs due to the difference in wavelength of light as it enters into the medium.

'Beats' is a phenomenon that occurs when frequencies of two harmonic waves arenearly same.

When two sound waves of nearly same frequencies, travelling in a medium, superimpose on each other, the intensity of the resultant sound at a particular position rises and falls regularly with time.This phenomenon of regular variation in the intensity of sound with time at a particular position is called beats.

Beat frequency: The number of beats produced per second is called a beat frequency.

From above it is clear that, the phenomenon of wavering of sound intensity when two waves of nearly the same frequencies and amplitudes travelling in the medium, are superimposed on each other is called beats.

Ampere's law

The circulation \(\oint B.dl\) of the resultant magnetic field along a closed, plane curve is equal to \(\mu_{0}\) times the total current crossing the area bounded by the closed curve provided the electric field inside the loop remains constant.

\(\oint B.dl =\mu_{0} \)i

Where, \(B\) is the magnetic field at the length element \(dl\) of the loop. i is the sum of all currents inside the loop.

The magnetic field B on the ampere loop element \(dl\) is due to all the current elements in the vicinity. But on the right-hand side of the equation, 'i' is the sum of all the currents inside the loop only.

The base emitter voltage in a cut off region is less than 0.7V.

From the cut off characteristics, the base emitter voltage (V_BE) in a cut off region is less than 0.7V. The cut off region can be considered as ‘off mode’. Here, V_BE > 0.7 and I_C=0. For a PNP transistor, the emitter potential must be negative with respect to the base.

Resistance \(R=\frac{\text { Potential difference }}{\text { current }}=\frac{V}{i}=\frac{W}{\frac{q}{t}}\)

(Because Potential difference is equal to work done per unit charge).

So, Dimensions of \(R\) \(=\frac{[\text { Dimensions of work }]}{[\text { Dimensions of charge] }[\text { Dimensions of current }]}\)

\(=\frac{\left[M L^{2} T^{-2}\right]}{[I T][I]}=\left[M L^{2} T^{-3} I^{-2}\right]\)