EACH INDIVIDUAL STUDENT SHOULD ATTEMPT ALL SETS OF QUESTION IN RESPONSE TO ELECTION VACATION.
SET 1
1. An electron moves in a circular path of radius 20 cm in a magnetic field of 2 × 10 -3 Tesla. Find the speed of the electron. What is the potential through which the electron must be accelerated to acquire this speed? Mass of electron= 9.1 × 10 -31 Kg
2. Light of frequency 5× 10 14 Hz liberates electrons with energy 2.31× 10 -19 J from a certain metallic surface. What is the wavelength of ultraviolet light which liberates electrons of energy 8.93 × 10 -19 J from the same surface? Speed of light= 3× 10 8 m/s, Planck’s constant = 6.62 × 10 -34 Js.
3. The energy liberated in the fission of single Uranium-235 atom is 3.2×10-11 J. Calculate the power production corresponding to the fission of 1 gm of uranium per day. Assume Avogadro constant as 6.02×1023 mole-1.
4. Two thin coherent sources of monochromatic light of wavelength 5000 A⁰ are separated by a distance of 0.2 mm. find the fringe width of the interference pattern formed by them on a screen 1 m away from the sources.
5. In double slit experiment, the slits are 0.3mm apart and interference is observed on a screen placed at a distance 90 cm from the slits. The second dark fringe is 0.3 cm from the central bright fringe. Find the wavelength of light used and the distance of the fourth bright fringe from central bright fringe.
6. A X-ray tube works at a dc potential difference of 50 KV. Only 0.4% of the energy of the cathode rays is converted into X-rays and heat generated in the target at the rate of 600 watt. Estimate the current passed into the tube and the velocity of the electrons striking the target. (Mass of electron=9.1×10-31 Kg, Charge of electron=1.6×10-19 C)
7. A beam of light after reflection at a plane mirror rotating 2000 times per minute passes a distant reflector. It returns to a rotating mirror from which it is reflected to make an angle of 1º with the original direction. Assuming that the velocity of light is 3×105 km/s calculate the distance between the mirrors.
SET 2
1. A light source consumes 75 W of electric power. If all this energy goes into emitted light of wavelength 600 nm. Calculate the frequency of the emitted light and the number of photons per second emitted by the source.
2. 400 nm wavelength of light falls on a photo sensitive material of work function 2.3 eV. Compute the maximum energy of photoelectrons.
3. Two plane metal plates 4cm long are held horizontally 3cm apart in a vacuum, one being vertically above the other. The upper plate is at potential of 300V and the lower plate is earthed. Electrons having a velocity of 107m/s are injected horizontally midway between the plates and in a direction parallel to the 4cm edge. Calculate the vertical deflection of the electron beam as it emerges from the plates.
4. An oil drop of mass 3.25×10-15kg falls vertically with uniform velocity, through the air between vertical parallel plates which are 2cm apart. When a p.d. of 1000V is applied to the plates the drop moves towards the negatively charged plate, its path being inclined at 45º to the vertical. Calculate the charge on the drop.
5. In Michelson’s arrangement for determining the speed of light , the distance between octagonal reflector and distant stationary mirror is 32 km. Determine the frequency of revolution to turn the octagonal reflector for forming image after reflection from succeeding reflector.
6. An electric heating element to dissipate 480 watts on 240 V mains is to be made from nichrome wire of 1 mm diameter. Calculate the length of the wire required if the resistivity of nichrome is 1.1×10-6 ohm-meter.
SET 3
1. A straight horizontal rod of length 20 cm and mass 30 gm is placed in a uniform horizontal magnetic field perpendicular to the rod. If a current of 2A through the rod makes it self supporting in the magnetic field, calculate the magnetic field.
2. A long solenoid of 1000 turns and cross sectional area 2×10-3 m2 carries a current of 2A and produces a flux density 52×10-3 T inside it. Calculate the self inductance of the coil.
3. A piano string 1.8 m long is made of steel of density 7800 kg/m3 and Young’s modulus 2× 1011 N/m2. It is maintained at a tension which produced an elastic strain of 1% in the string. Calculate the frequency of transverse vibration of the string when it is vibrating in second mode of vibration.
4. In Young’s double slit experiment, we observe the 10th bright fringe for λ=6000A⁰. What order will be visible if the source of light is replaced by light of wavelength 5000 A⁰?
5. When light of frequency 5.4×1014 Hz, liberated electrons with energy 2.31×10-19 J from a certain metallic surface. What is the wavelength of ultraviolet light which liberates electron of energy 8.93×10-19J from the same surface?
6. The photoelectric work function of potassium is 2eV and the surface is illuminate with radiation of wavelength 350nm. What potential differences have to be applied between a potassium surface and the collecting electrode in order just to prevent collection of electrons? What would be the kinetic energy of electrons?
7. When ultraviolet light with wavelength of 400 nm falls on a certain metal surface, the maximum kinetic energy of the emitted photoelectron is 1.1 eV. What is the maximum kinetic energy of the photoelectrons when light of wavelength 300nm falls on the same surface?
SET 4
1. An electron is accelerated through a potential difference of 2000V and then enters a uniform magnetic field of 0.02T in a direction perpendicular to it. Find the radius of the path of the electron in the magnetic field.
2. Calculate the radius of a water drop which would just remain suspended in an electric field of 300V/cm and charged with one electron.
3. An electron beam after being accelerated from rest through a potential difference of 5KV in vacuum is allowed to impinge normally on a fixed surface. If the incident current is 50µA, determine the force exerted on the surface assuming that it brings the electrons to rest.
4. In a Thomson experiment voltage across the plates is 50V and the distance between them is 3cm. The magnetic field applied to make the beam undeflected is 10-4T. What is the velocity of the electron passing between the plates?
5. If the frequency of fundamental note of a closed organ pipe and that of an open organ pipe are the same, what will be the ratio between their lengths?
6. A uniform tube 60 cm long stands vertically with its lower end dipping into water. When the length above the water is 14.8 cm and again when it is 48 cm, the tube resounds to a vibrating tuning fork of frequency 512 Hz. Find the lowest frequency to which the tube will resound when it is open at both ends.
7. An open pipe 30 cm long and a closed pipe 23 cm long, both of the same diameters, are each sounding its first overtone, and these are in resonance. What is the end correction of these pipes?
SET 5
1. A piano string 1.8 m long is made of steel of density 7800 kg/m3 and Young’s modulus 2× 1011 N/m2. It is maintained at a tension which produced an elastic strain of 1% in the string. Calculate the frequency of transverse vibration of the string when it is vibrating in second mode of vibration.
2. A wire with mass 50 gm is stretched so that its ends are tied down at points 80 cm apart. The wire vibrates in the fundamental mode with frequency 60 Hz. Calculate the speed of propagation of transverse waves in the wire and tension in the wire.
3. In a resonance tube experiment, the first and the second resonance positions were observed at 17 cm and 52.6 cm respectively. The tuning fork used was of frequency 512 Hz and the temperature was 27ᴼC. Calculate the velocity of sound in air at 0ᴼC and end correction of the tube.
4. A wire under tension vibrates with a fundamental frequency of 240 Hz. What would be the fundamental frequency if the wire were half as long, twice as thick and under one fourth of the tension?
5. Light passes through a single crystal of ruby 25 m long and emerges with a wavelength of 6.4×10-7 m . If the refractive index of ruby is 1.6, calculate the number of wavelengths inside the crystal.
6. In Foucault’s method for the velocity of light the distance between the moving and static mirrors was 3 km and the speed of the moving mirror was 500 rev/sec. If the displacement of the returned beam is 7 º12’
, find the velocity of light.
7. In Michelson’s method to measure the speed of light, a strong source of light is reflected from one face of an octagonal equiangular mirror and travels a distance of 35 km to a stationary mirror from which it returns and after second reflection from octagonal mirror forms an image of the source on a screen. What is the angular speed of rotation of the rotating mirror?
SET 1
1. An electron moves in a circular path of radius 20 cm in a magnetic field of 2 × 10 -3 Tesla. Find the speed of the electron. What is the potential through which the electron must be accelerated to acquire this speed? Mass of electron= 9.1 × 10 -31 Kg
2. Light of frequency 5× 10 14 Hz liberates electrons with energy 2.31× 10 -19 J from a certain metallic surface. What is the wavelength of ultraviolet light which liberates electrons of energy 8.93 × 10 -19 J from the same surface? Speed of light= 3× 10 8 m/s, Planck’s constant = 6.62 × 10 -34 Js.
3. The energy liberated in the fission of single Uranium-235 atom is 3.2×10-11 J. Calculate the power production corresponding to the fission of 1 gm of uranium per day. Assume Avogadro constant as 6.02×1023 mole-1.
4. Two thin coherent sources of monochromatic light of wavelength 5000 A⁰ are separated by a distance of 0.2 mm. find the fringe width of the interference pattern formed by them on a screen 1 m away from the sources.
5. In double slit experiment, the slits are 0.3mm apart and interference is observed on a screen placed at a distance 90 cm from the slits. The second dark fringe is 0.3 cm from the central bright fringe. Find the wavelength of light used and the distance of the fourth bright fringe from central bright fringe.
6. A X-ray tube works at a dc potential difference of 50 KV. Only 0.4% of the energy of the cathode rays is converted into X-rays and heat generated in the target at the rate of 600 watt. Estimate the current passed into the tube and the velocity of the electrons striking the target. (Mass of electron=9.1×10-31 Kg, Charge of electron=1.6×10-19 C)
7. A beam of light after reflection at a plane mirror rotating 2000 times per minute passes a distant reflector. It returns to a rotating mirror from which it is reflected to make an angle of 1º with the original direction. Assuming that the velocity of light is 3×105 km/s calculate the distance between the mirrors.
SET 2
1. A light source consumes 75 W of electric power. If all this energy goes into emitted light of wavelength 600 nm. Calculate the frequency of the emitted light and the number of photons per second emitted by the source.
2. 400 nm wavelength of light falls on a photo sensitive material of work function 2.3 eV. Compute the maximum energy of photoelectrons.
3. Two plane metal plates 4cm long are held horizontally 3cm apart in a vacuum, one being vertically above the other. The upper plate is at potential of 300V and the lower plate is earthed. Electrons having a velocity of 107m/s are injected horizontally midway between the plates and in a direction parallel to the 4cm edge. Calculate the vertical deflection of the electron beam as it emerges from the plates.
4. An oil drop of mass 3.25×10-15kg falls vertically with uniform velocity, through the air between vertical parallel plates which are 2cm apart. When a p.d. of 1000V is applied to the plates the drop moves towards the negatively charged plate, its path being inclined at 45º to the vertical. Calculate the charge on the drop.
5. In Michelson’s arrangement for determining the speed of light , the distance between octagonal reflector and distant stationary mirror is 32 km. Determine the frequency of revolution to turn the octagonal reflector for forming image after reflection from succeeding reflector.
6. An electric heating element to dissipate 480 watts on 240 V mains is to be made from nichrome wire of 1 mm diameter. Calculate the length of the wire required if the resistivity of nichrome is 1.1×10-6 ohm-meter.
SET 3
1. A straight horizontal rod of length 20 cm and mass 30 gm is placed in a uniform horizontal magnetic field perpendicular to the rod. If a current of 2A through the rod makes it self supporting in the magnetic field, calculate the magnetic field.
2. A long solenoid of 1000 turns and cross sectional area 2×10-3 m2 carries a current of 2A and produces a flux density 52×10-3 T inside it. Calculate the self inductance of the coil.
3. A piano string 1.8 m long is made of steel of density 7800 kg/m3 and Young’s modulus 2× 1011 N/m2. It is maintained at a tension which produced an elastic strain of 1% in the string. Calculate the frequency of transverse vibration of the string when it is vibrating in second mode of vibration.
4. In Young’s double slit experiment, we observe the 10th bright fringe for λ=6000A⁰. What order will be visible if the source of light is replaced by light of wavelength 5000 A⁰?
5. When light of frequency 5.4×1014 Hz, liberated electrons with energy 2.31×10-19 J from a certain metallic surface. What is the wavelength of ultraviolet light which liberates electron of energy 8.93×10-19J from the same surface?
6. The photoelectric work function of potassium is 2eV and the surface is illuminate with radiation of wavelength 350nm. What potential differences have to be applied between a potassium surface and the collecting electrode in order just to prevent collection of electrons? What would be the kinetic energy of electrons?
7. When ultraviolet light with wavelength of 400 nm falls on a certain metal surface, the maximum kinetic energy of the emitted photoelectron is 1.1 eV. What is the maximum kinetic energy of the photoelectrons when light of wavelength 300nm falls on the same surface?
SET 4
1. An electron is accelerated through a potential difference of 2000V and then enters a uniform magnetic field of 0.02T in a direction perpendicular to it. Find the radius of the path of the electron in the magnetic field.
2. Calculate the radius of a water drop which would just remain suspended in an electric field of 300V/cm and charged with one electron.
3. An electron beam after being accelerated from rest through a potential difference of 5KV in vacuum is allowed to impinge normally on a fixed surface. If the incident current is 50µA, determine the force exerted on the surface assuming that it brings the electrons to rest.
4. In a Thomson experiment voltage across the plates is 50V and the distance between them is 3cm. The magnetic field applied to make the beam undeflected is 10-4T. What is the velocity of the electron passing between the plates?
5. If the frequency of fundamental note of a closed organ pipe and that of an open organ pipe are the same, what will be the ratio between their lengths?
6. A uniform tube 60 cm long stands vertically with its lower end dipping into water. When the length above the water is 14.8 cm and again when it is 48 cm, the tube resounds to a vibrating tuning fork of frequency 512 Hz. Find the lowest frequency to which the tube will resound when it is open at both ends.
7. An open pipe 30 cm long and a closed pipe 23 cm long, both of the same diameters, are each sounding its first overtone, and these are in resonance. What is the end correction of these pipes?
SET 5
1. A piano string 1.8 m long is made of steel of density 7800 kg/m3 and Young’s modulus 2× 1011 N/m2. It is maintained at a tension which produced an elastic strain of 1% in the string. Calculate the frequency of transverse vibration of the string when it is vibrating in second mode of vibration.
2. A wire with mass 50 gm is stretched so that its ends are tied down at points 80 cm apart. The wire vibrates in the fundamental mode with frequency 60 Hz. Calculate the speed of propagation of transverse waves in the wire and tension in the wire.
3. In a resonance tube experiment, the first and the second resonance positions were observed at 17 cm and 52.6 cm respectively. The tuning fork used was of frequency 512 Hz and the temperature was 27ᴼC. Calculate the velocity of sound in air at 0ᴼC and end correction of the tube.
4. A wire under tension vibrates with a fundamental frequency of 240 Hz. What would be the fundamental frequency if the wire were half as long, twice as thick and under one fourth of the tension?
5. Light passes through a single crystal of ruby 25 m long and emerges with a wavelength of 6.4×10-7 m . If the refractive index of ruby is 1.6, calculate the number of wavelengths inside the crystal.
6. In Foucault’s method for the velocity of light the distance between the moving and static mirrors was 3 km and the speed of the moving mirror was 500 rev/sec. If the displacement of the returned beam is 7 º12’
, find the velocity of light. 7. In Michelson’s method to measure the speed of light, a strong source of light is reflected from one face of an octagonal equiangular mirror and travels a distance of 35 km to a stationary mirror from which it returns and after second reflection from octagonal mirror forms an image of the source on a screen. What is the angular speed of rotation of the rotating mirror?
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