PHYS 1070 Lab 5_ Electrical Resistance and Ohm's Law

The resistance of wire increases from 40 – ohm at 20 0C to 50 – ohm at 70 0C. Find the temperature coefficient of resistance at 0 0C.

6. Use this information to answer Question 6-7: Photoconductive detector detects light by measuring the changes in resistance caused by light illumination. Consider an n-type Si rectangular bar with a length L = 1 cm, width W = 0.5 mm and thickness t = 5.0 um. Doping density is Np = 1014 cm. Calculate the resistance when it is placed in the dark. Give your answer in unit of N. Answers within 5% error will be considered correct. 1851851 Correct 7. The top surface (1 cm x 0.5 mm) is now uniformly illuminated by monochromatic light at 1.3 ev with power density of 0.3 W/cm?. Calculate the resistance under this condition. Absorption coefficient of silicon at the wavelength of illumination is 1 x 10° cm-1 and the carrie lifetime is = T, = 10-6 s. A simple approximation is to calculate the carrier generation rate by multiplying incident photon fiux with absorption coefficient. Give your answer in unit of 2. Answers within 5% error will be considered correct. 88118.41787 Correct

nichrome ribbon resistor elements each has a resistance of 1 ohm. the element is made from sheet of nichrome alloy, 0.025 cm thick. if the width 9f the ribbon is 0.3 cm , what is the length is required per element? assume specific resistance of nichrome alloy to be 10g micro ohm-cm

b) Describe the traces you would see on an oscilloscope monitoring voltage changes across a resistance which has: - AC flowing through it - DC flowing through it You should include diagrams to support your descriptions for each trace.

In the figure the ideal batteries have emfs ɛ1 = 20.4 V, ɛ2 = 9.05 V, and ɛ3 = 5.40 V, and the resistances are each 2.40 Q. What are the (a) size and (b) direction (left or right) of current i,? (c) Does battery 1 supply or absorb energy, and (d) what is its power? (e) Does battery 2 supply or absorb energy, and (f) what is its power? (g) Does battery 3 supply or absorb energy, and (h) what is its power? (a) Number i Units (b) (c) (d) Number i Units (e) (f) Number i Units (g) (h) Number i Units

3. The figure on the left below shows a schematic diagram of a battery. The voltage measured by U1 is called the terminal voltage given R1 = 1 ohm. In the figure on the right below, the terminal voltage of each of the battery-resistor combination is Vr = 1.5 volts. Find the following: a. The current passing through R5. b. The currents passing through R1 and R3 C. The voltage across R1. d. The voltage of the battery EMF. e. The percentage of voltage loss ot the battery due to the internal resistance R1. The power dissipated by the internal resistance R1. g. The power dissipated by R5 if R1 = R2 = R3 = R4 = 0. h. The percentage of power dissipation loss due to the four resistors R1, R2, R3, and R4 f. R1 R3 S10 R1 U1 1.500 EMF EMF R5 100 V1 R2 $10 EMF R4 EMF EMF

A fuse wire of circular cross-section has a radius of 0.8 mm. The wire blows off at a current of 8A. Calculate the radius of the wire that will blow off at a current of 1 A. Also calculate the Value of blow off current when radius is 0.5 mm

A rubber rod is rubbed with fur, so that the fur becomes positive. The rod is then used to charge an electroscope. The charge on the electroscope will be:positive if charged by contact. neutral. positive if charged by induction.negative if charged by induction.

How about solving this using KCL equations? Thank you

Question 3 a. Some materials exhibit the property of superconductivity under certain conditions. State what is meant by superconductivity and explain the required conditions for the material to become superconducting. b. The diagram below shows the cross-section of a cable consisting of parallel filaments that can be made superconducting, embedded in a cylinder of copper. copper cylinder filament The cross-sectional area of the copper in the cable is 2.28 x 10-7 m². The resistance of the copper in a 1.0 m length of the cable is 0.075 N. Calculate the resistivity of the copper, stating an appropriate unit. State and explain the what happen to the resistance of the cable when the embedded filaments of wire are made superconductive? i.

A copper wire has a resistance of 0.85 ohm at 200C. What will be its resistance at 400C ? Temperature coefficient of resistance of copper at 00C is 0.004/0C.