## Sunday, 28 February 2016

## Sunday, 21 February 2016

### F.Sc ICS Notes: Physics XII: Chapter 14 Electromagnetism Numerical Problems

## F.Sc ICS Notes: Physics XII: Chapter 14 Electromagnetism Numerical Problems

__Find the value of the magnetic field that will cause a maximum force of 7 * 10(-3) N on a 20cm straight wire carrying current of 10 A.__

**Numerical Problem 14.1:**__How fast must a proton move in a magnetic field 2.5 * 10(-3) T such that the magnetic force is equal to its weight?__

**Numerical Problem 14.2:**__A velocity selector has a magnetic field of 0.3T. If a perpendicular electric field of 10000V/m is applied, what will be the speed pf the particle that will pass through the selector?__

**Numerical Problem 14.3:**__A coil of 0.1m * 0.1m and of 200 turns carrying a current of 1 mA is placed in a uniform magnetic field of 0.1T. Calculate the maximum torque that acts on the coil.__

**Numerical Problem 14.4:**__A power line 10m high carries a current 200A. Find the magnetic field of the wire at the ground.__

**Numerical Problem 14.5:**__You are asked to design a solenoid that will give a magnetic field of 0.1 T, yet the current must not exceed 10 A. Find the number of turns per unit length that the solenoid should have.__

**Numerical Problem 14.6:**__What current should pass through a solenoid that is 0.5m long with 10000 turns of copper wire so that it will have a magnetic field of 0.4T.__

**Numerical Problem 14.7:**__A galvanometer having an internal resistance Rg = 15 ohm gives full scale deflection with current Ig = 10 mA. It is to be converted into an ammeter of range 10 A. Find the value of shunt resistance Rs?__

**Numerical Problem 14.8:**__The resistance of galvanometer is 50 ohm and reads full-scale deflection with a current of 2mA. Shown by a diagram on book how to convert this galvanometer into a voltmeter reading 200V full scale.__

**Numerical Problem 14.9:**__The resistance of galvanometer coil is 10 ohm and reads full scale with a current of 1 mA. What should be the values of resistance R1, R2, and R3 to convert this galvanometer into a multi-range ammeter of 100, 10, and 1A as shown in figure on book.__

**Numerical Problem 14.10:**### Written by: Asad Hussain

### F.Sc ICS Notes: Physics XII: Chapter 13 Current Electricity Numerical Problems

## F.Sc ICS Notes: Physics XII: Chapter 13 Current Electricity Numerical Problems

__How many electrons pass through an electric bulb in one minute if the 300 mA current is passing through it?__

**Numerical Problem 13.1:**__A charge of 90 C passes through a wire in 1 hour and 15 minutes. What is the current in the wire?__

**Numerical Problem 13.2:**__Find the equivalent resistance of this circuit, total current drawn from the source and the current through each resistor.__

**Numerical Problem 13.3:**__A rectangular bar of iron is 2cm by 2cm in cross section and 40cm long. Calculate its resistance if the resistivity of iron is 11 * 10(-8) ohm-meter.__

**Numerical Problem 13.4:**__The resistance of an iron wire at 0 degree is 1 * 10(4) ohm. What is the resistance at 500 degree if the temperature coefficient of resistance of iron is 5.2 * 10(-3) per kelvin?__

**Numerical Problem 13.5:**__Calculate terminal potential difference of each of cells in circuit of figure on the book.__

**Numerical Problem 13.6:**__Find the current which flows in all the resistances of the circuit of figure on the book.__

**Numerical Problem 13.7:**__Find the current and power dissipated in each resistance of the circuit, shown in figure on the book.__

**Numerical Problem 13.8:**### Written by: Asad Hussain

### F.Sc ICS Notes: Physics XII: Chapter 15 Electromagnetic Induction Numerical Problems

## F.Sc ICS Notes: Physics XII: Chapter 15 Electromagnetic Induction Numerical Problems

__An EMF of 0.45V is induced between the ends of a metal bar moving through a magnetic field of 0.22T. What field strength would be needed on EMF of 1.5 V bet. The ends of the bar, assuming that all other factors remain the same?__

**Numerical Problem 15.1:**__The flux density B in a region between the pole faces of a horse shoe magnet 0.5 wb/m(2) directed vertically downwards. Find the EMF induced in a straight wire 5cm long, perpendicular to B when it is moved in a direction at an angle of 60degree with the horizontal with a speed of 100cm/s.__

**Numerical Problem 15.2:**__A coil of wire has 10 loop. Each loop has an area of 1.5 * 10 (-3)m(2). A magnetic field perpendicular to the surface of each loop at all times. If the magnetic field is charged from 0.05T to 0.06T in 0.1 sec. Find the average EMF induced in the coil during this time.__

**Numerical Problem 15.3:**__A circular coil has 15 turns of radius 2cm each. The plane of the coil is inclined at 40 degree to a uniform magnetic field of 0.2T. If the field is increased to 0.5T in 0.2 sec, find the magnitude of the induced EMF.__

**Numerical Problem 15.4:**__Two coils are placed side by side. An EMF of 0.8V is observed in one coil when the current is changing at the rate of 200 A/s in the other coil. What is the mutual inductance of the coils?__

**Numerical Problem 15.5:**__A pair of adjacent coils has a mutual inductance of 0.1H. If the current in the primary changes from 0 to 10 A in 0.25s, what is the average induced EMF in the secondary? What is the change in flux in it if the secondary has 500 turns?__

**Numerical Problem 15.6:**__A solenoid has 250 turns and its self inductance is 2.4 mH. What is the flux through each turn when the current is 2A? What is the induced EMF when the current changes at 20 A/s?__

**Numerical Problem 15.7:**__A solenoid of length 8cm and cross sectional area 0.5cm(2) turns. Find the self inductance of the solenoid when the core is air. If the current in the solenoid increases through 1.5A in 0.2 sec, find the magnitude of induced EMF in it.__

**Numerical Problem 15.8:**__When current through a cell changes from 100 mA to 200 mA in 0.005 sec, an induced EMF of 40 mV is produced in the coil.__

**Numerical Problem 15.9:**(a) What is the self inductance of the coil?

(b) Find the increase in the energy stored in the coil.

__Like any field, the Earth's magnetic field stores energy. Find the magnetic energy stored in a space where strength of earth's field is 7 * 10(-5) T, if the space occupies an area of 10 * 10(8)m(2) and has a height of 750m.__

**Numerical Problem 15.10:**__A square coil of side 16cm has 200 turns and rotates in uniform magnetic field of magnitude 0.05 T. If the peak EMF is 12 V, what is the angular velocity of the cell?__

**Numerical Problem 15.11:**__A generator has a rectangular coil consisting of 360 turns. The coil rotates at 420 rev per min in 0.14 T magnetic field. The peak value of EMF produced by the generator is 50 V. If the coil is 5 cm wide, find the length of the side of the coil.__

**Numerical Problem 15.12:**__It is desired to make an A.C generator that can produce an EMF of 5kV with 50Hz frequency. A coil of area 1m(2) consisting of 200 turns is used as armature. What should be the magnitude of the magnetic field in which the coil rotates?__

**Numerical Problem 15.13:**__The back EMF in a motor is 120 V when the motor is turning at 1680 rev/min. What is the back EMF when the motor turns at 3360 rev/min?__

**Numerical Problem 15.14:**__A D.C motor operates at 240V and has a resistance of 0.5 ohm. When the motor is running at normal speed, the armature is 15A. Find the back EMF in the armature.__

**Numerical Problem 15.15:**__A copper ring has radius of 4cm and resistance of 1 milli ohm. A magnetic field applied over the ring, perpendicular to its plane. If the magnetic field increases from 0.2 T to 0.4 T in a time interval of 5 * 10(-3)s. What is the current in the ring during?__

**Numerical Problem 15.16:**__A coil of 10 turns and 35 cm(2) area is in a perpendicular magnetic field of 0.5T. The coil is pulled out of the field in 1s. Find the induced EMF in the coil as it is pulled out of the field.__

**Numerical Problem 15.17:**__An ideal step down transformer is connected to main supply of 240V. It is desired to operate a 12V, 30W lamp. Find the current in the primary and the transformation ratio?__

**Numerical Problem 15.18:**### Written by: Asad Hussain

### F.Sc ICS Notes: Physics XII: Chapter 17 Physics of Solids Numerical Problems

## F.Sc ICS Notes: Physics XII: Chapter 17 Physics of Solids Numerical Problems

**A 1.25 cm diameter cylinder is subjected to a load of 2500 kg. Calculate the stress on the bar in mega pascals?**

__Numerical Problem: 17.1__**A 1.0 m long wire is subjected to stretching force and its length increases by 20 cm, Calculate the tensile strain and the percent elongation which the wire undergoes?**

__Numerical Problem: 17.2__**A wire 2.5 m long and cross section are 10(-5) m(2) is stretched 1.5 mm by a force of 100 N in the elastic region. Calculate.**

__Numerical Problem: 17.3__**(i)**Strain

**(ii)**Young's Modulus

**(iii)**The energy stored in wire = U =?

**What stress would cause a wire to increase in length by 0.01 % if the Young's Modulus of the wire is 12 * 10(10) Pa. What force would produce this stress if the diameter of wire is 0.56 mm?**

__Numerical Problem: 17.4__**The length of a steel wire is 1.0 m and its cross sectional area is 0.03 * 10(-4) m(2). Calculate the work done in stretching the wire where force of 100 N is applied with in the elastic region. Young's Modulus of steel is 3 * 0 (11) Nm(-2).**

__Numerical Problem: 17.5__**A cylindrical copper wire and a cylindrical steel wire each of length 1.5 and diameter 2.0 mm are joined one end to form a composite wire of 3.0 m long. The wire is loaded until its length becomes 3.003 m. Calculate the strain in copper and steel wire and the force applied to the wire. (Young's Modules of Copper is 1.2 * 10(11) Pa and for steel is 2.0 * 10(11) Pa).**

__Numerical Problem: 17.6__### Written by Asad Hussain

### F.Sc ICS Notes: Physics XII: Chapter 18 Electronics Numerical Problems

## F.Sc ICS Notes: Physics XII: Chapter 18 Electronics Numerical Problems

__The current flowing into the base of a transistor is 100 micro Ampere. Find its collector current Ic. its emitter current Te and the ratio Ic/Ie, if the value of current gain Î² is 100.__

**Numerical Problem: 18.1**__Figure on book shows a transistor which operates a relay as the switch S is closed. The relay is energized by a current of 10m A. Calculate the value Rg which will just make the relay operate . The current gain Î² of the transistor is 200. When the transistor conducts, its Vbe can be assumed to 0.6 Volt.__

**Numerical Problem: 18.2**__In circuit shown on the book figure, there is negligible potential drop between B and E, where is Î² is 100, calculate:__

**Numerical Problem: 18.3****(i)**base current

**(ii)**collector current

**(iii)**potential drop across Rc

**(iv)**Vce

__Calculate the output of the op-amp circuit shown in figure on book.__

**Numerical Problem: 18.4**__Calculate the gain of the non-inverting amplifier as in figure on book.__

**Numerical Problem: 18.5**__Calculate the gain of an amplifier in which the collector resistance Rc is 5 kilo Ohm. The input resistance between the base and emitter of a typical transistor is 2.5 kilo Ohm and the value of its Î² = 100.__

**Numerical Problem: 18.6**### Written by: Asad Hussain

### F.Sc ICS Notes: Physics XII: Chapter 12 Electrostatics Numerical Problems

## F.Sc ICS Notes: Physics XII: Chapter 12 Electrostatics Numerical Problems

__Compare magnitudes of electrical and gravitational force exerted on an object (mass 20 g charge = 20 micro C) by an identical object that is placed 10 cm from the first. (G = 6.67 * 10(-11) Nm(2)kg(-2))__

**Numerical Problem 12.1:**__Calculate the net electrostatic force on q as shown in the figure on book.__

**Numerical Problem 12.2**__A point charge q = -8 * 10(-8) C is placed at the origin. Calculate electric field at a point 2 m from the origin on the z axis?__

**Numerical Problem 12.3**__Determine the electric field at the position r = (4i + 3j) m caused by as point charge q = 5 * 10(-6) placed at origin.__

**Numerical Problem 12.4**__Two point charges, q1 = -1 * 10(-6) C and q2 = 4 * 10(-6) C, separated by a distance of 3 m. Find and justify the zero field location.__

**Numerical Problem 12.5**__Find the electric field strength required to hold suspended particle of mass 1 * 10(-6) kg and charge 1 micro C between two plates 10 cm apart.__

**Numerical Problem 12.6**__A particle having a charge of 20 electrons on it falls through a potential difference of 100 volts. Calculate the energy acquired by it in electron volts (eV).__

**Numerical Problem 12.7**__In Millikan's experiment, oil droplets are introduced into the space between two flat horizontal plates, 500 mm apart. The plate voltage is adjusted to exactly 780 Volts so that the droplet is held stationary. The plate voltage is switched off and the selected droplet is observed to fall a measured distance of 1.50 mm in 11.2 s. Given that the density of the oil used is 9000kgm(-3), and the viscosity of air at laboratory temperature is 1.8 * 10(-5) Nm(-2)s, calculate:__

**Numerical Problem 12.8****(a)**the mass, and

**(b)**the charge on the droplet (assume g = 9.8 ms(-2))

__A proton placed in uniform electric field of 5000 NC(-1) directed to right is allowed to go a distance of 10 cm from A to B. Calculate:__

**Numerical Problem 12.9****(a)**Potential difference between the two points

**(b)**Work done

**(c)**The change in Potential Energy of the proton

**(d)**The change in Kinetic Energy of the proton

**(e)**Its velocity (mass of proton is 1.67 * 10(27) kg)

__Using zero reference point at infinity, determine the amount by which a point charge of 4 * 10(-8) C alters the electric potential at point 1.2m away, when__

**Numerical Problem 12.10****(a)**charge is positive

**(b)**charge is negative

__In Bohr's atomic model of hydrogen atom, the electron is in an orbit around the nuclear proton at a distance of 5.29 * 10(-11) m with a speed of 2.18 8 10(6) m/s.__

**Numerical Problem 12.11****(a)**The electric potential that a proton exerts at this distance.

**(b)**Total energy of the atom in eV.

**(c)**The ionization energy for the atom in eV.

__The electrostatic flash attachment for a camera contains a capacitor for storing energy used to produce the flash. In one such unit, the potential difference between the plates of a 750 micro Farad capacitor is 330 Volt. Determine the energy that is used to produce the flash.__

**Numerical Problem 12.12**__A capacitor has a capacitance of 2.5 * 10(-8) Farad. In the changing process, electrons removed from one plate and placed on the other one. When the potential difference between the plates is 450 volt, how many electrons have been transferred? (e = 1.60 * 10(-19) Coulomb)__

**Numerical Problem 12.13**### Written by: Asad Hussain

Subscribe to:
Posts (Atom)