In a photoelectric cell, the collector and emitter plates are separated by a distance of 15 cm. The photocell is connected with an ammeter in series. When white light [λ (wavelength) between 400 nm−700 nm] falls on this plate (work function =2.1 eV), a current flows through the ammeter. A magnetic field is now switched on between the plates as shown in the figure. As this field is increased, the current through the ammeter decreases and finally becomes zero. The minimum magnetic field, for which the ammeter current becomes zero, is found to be (0.45×10−5b Tesla, where ‘b′ is close to an integer. Find the value of b. Assume that all the photoelectrons are emitted normally from the emitter.

In a photoelectric cell, the collector and emitter plates are separate

1.	In a photoelectric cell, the collector and emitter plates are separated by a distance of 15 cm. The photocell is connected with an ammeter in series. When white light [λ (wavelength) between 400 nm−700 nm] falls on this plate (work function =2.1 eV), a current flows through the ammeter. A magnetic field is now switched on between the plates as shown in the figure. As this field is increased, the current through the ammeter decreases and finally becomes zero. The minimum magnetic field, for which the ammeter current becomes zero, is found to be (0.45×10−5b Tesla, where ‘b′ is close to an integer. Find the value of b. Assume that all the photoelectrons are emitted normally from the emitter.
Answer» In a photoelectric cell, the collector and emitter plates are separated by a distance of $15 cm$ . The photocell is connected with an ammeter in series. When white light [ $λ$ (wavelength) between $400 nm - 700 nm$ ] falls on this plate (work function $= 2.1 eV$ ), a current flows through the ammeter. A magnetic field is now switched on between the plates as shown in the figure. As this field is increased, the current through the ammeter decreases and finally becomes zero. The minimum magnetic field, for which the ammeter current becomes zero, is found to be (0.45 $\times 10^{- 5} b$ Tesla, where $‘ b^{'}$ is close to an integer. Find the value of $b$ . Assume that all the photoelectrons are emitted normally from the emitter.

Discussion

No Comment Found

Related InterviewSolutions

One end of a steel wire is fixed to the ceiling of a moving elevator. A load of 20 kg hangs from the other end. If the elevator is moving up with an acceleration 1 m/s2 and Area of cross- section of wire is 2 cm2 then find the longitudnal strain in the wire.[Take g=10 ms−2,Y=2×1011 Nm−2 ]
Current i0 is being carried by an infinite wire passing through origin along the direction i^+ j^ + k^. Find magnetic field due to the wire at point (1m,0,0).
areunit vectors along x-and y-axisrespectively. What is the magnitude and direction of thevectorsand?What are the components of a vectoralongthe directions of and?[You may use graphical method]
A parallel-plate capacitor having plate area A and plate separation d is joined to a battery of emf E and internal resistance R at t=0. Consider a plane surface of area A/2, parallel to the plates and situated symmetrically between them. If the displacement current through this surface as a function of time is given as:id=EnRe−tdε0ARWhere, ε0 is the permittivity of free space.The value of n is :
A horizontal curve with superelevation e = 0.05 (note, e=tanβ ) has a posted speed limit of 60 km/h. For this speed limit, only those vehicles with Y/X ratio(in figure) greater than 2 and travelling at speeds greater than 1.2 times the speed limit, will overturn. However, with recent increase in truck traffic the speed limit needs to be modified such that only those vehicles with Y/X ratio greater than 3 and travelling at more than 1.2 times the speed limit will overturn. What should be the new speed limit?(in km/hr round off to integer) (with respect to the figure, assume that the vehicle is travelling into the plane of the paper).50
Anair-cored solenoid with length 30 cm, area of cross-section 25 cm2and number of turns 500, carries a current of 2.5 A. The current issuddenly switched off in a brief time of 10−3s. How much is the average back emf induced across the ends of theopen switch in the circuit? Ignore the variation in magnetic fieldnear the ends of the solenoid.
A block of mass 30.0 kg is being brought down by a chain. If the block acquires a speed of 40.0 cms in dropping down 2.00 m, find the work done by the chain during the process.
The electric current in an X- ray tube (from the target to the filament) operating at 40 kV is 10 mA. Assume that on an average, 1% of the total kinetic energy of the electrons hitting the target are converted into X−rays. The total power (in W) emitted as X-rays is (Integer only)
If y=4x2x3+3, then dydx=
Two metal spheres (radii r1,r2 with r1<r2) are very far apart but are connected by a thin wire. If their combined charge is Q, then what is their common Potential?

Discussion

No Comment Found

Related InterviewSolutions

Reply to Comment