4. A well-insulated electric water heater, consisting of a coil made of Nichrome, can warm 5.0L of water from 20.0°C to 49°C in 20 minutes. Density of water = 1 g/cm3 Specific heat of water = 4.186 J/g.°C Resistivity of Nichrome = 1.1x10-6 Ω.m Temperature Coefficient of Nichrome = 0.00041/°C Density of Nichrome = 8.4 g/cm3 (a) How much power is the water heater drawing if the heater has an efficiency of 90%? (b) The water heater is connected to a 240V source. Calculate the resistance of the coil. (c) The total mass of the nichrome coil is 800g. Find the length and diameter of the wire.

2. A 50 m long wire with a cross-sectional area of 5.5 mm2 has a resistance of 31 Ω at 0 °C. Calculate the resistivity of the wire at 60 °C if the temperature coefficient of resistance at 0 °C is 0.0003 per °C.

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4. Calculate the number of ion pairs produced by an electron with kinetic energy of 1.0 MeV passing through a 30 mm thick ionization chamber. What is the total charge of electrons? If a hundred such particles pass through the chamber each second and all the ions are collected at the electrodes what is the total current? (The density of the gas is 1.3 kg/m³, the mass stopping power for air for 1.0 MeV is 1.67 MeV/(g/cm2) and it takes about 34 eV to produce an ion pair in air).

2. Calculate the current density in a copper wire at 20°C, if an electric field of 0.470 V/m exists in the wire. The resistivity of copper is 1.7 x 10-8 N. m.

3. Water, specific heat capacity c = 4.186 joules/gram C, flows through an insulated plastic pipe at a flow rate of 16.0 grams/sec. The water enters the pipe at a temperature of 10 C and leaves at a temperature of 80 C. The water is heated by an electric heater in the middle of the pipe. What is the Power output of the electric heater? 4. The resistance of a resistor changes with temperature; the equation is given as: R= a T^2 + bT+ C. The resistance was measured at three different temperatures. (20 C, 521 ohms), (60 C, 1329 ohms), (100 C, 2925 ohms). What are the values of a, b, and c for this resistor? ( hint: create three equations, solve for the unknowns ab.and c using simultaneous equations.

02:11 A A A V 14 Ó 41% a. Accurate only c. Neither precise nor accurate b. Precise only d. Both precise and accurate 3. Which type of errors occurs in measurements of temperature due to poor thermal contact between the thermometer and the substance whose temperature is to be found? a. systematic errors b. random errors c. both systematic and random errors d. neither systematic nor random errors 4. Which type of errors occurs in the fluctuations in line voltage, temperature, or mechanical vibrations of equipment? a. systematic errors b. random errors c. both systematic and random errors d. neither systematic nor random errors 5. The scores obtained by six students are : ( 45 , 32, 46, 39 ,36 , 48) Find the mean. C. 42 A. 40 B. 41 D. 43 6. Find the variance of the following set of data ( 2.44 m, 2.36 m, 2.48m, 2.35 m, 2.59 m) C.0.00 77 03m? D. 0.00 7704 m² A. 0.00 7701 m? B. 0.00 7702 m? refers to the numerical value or size C. scalar D. magnitude 7. A. vector B. force quantity has both…

3. The resistance of a uniform copper wire 50.0 meters long and 1.15 mm in diameter is 0.830 ohms at 20° C. What is the resistivity of the copper at this temperature? 4. A 200 m long aluminum wire has the same resistance and cross-sectional area as a carbon wire. What is the length of the carbon wire?

1. At 20.0°C, the carbon resistor in an electric circuit connected to a 5.0 V battery has a resistance of 2.0 x 1020. What is the current in the circuit when the temperature of the carbon rises to 80.0°C? (a = -0.5 x 10-31)

1. The variation in electrical resistance with temperature can be used to make precise temperature measurements. Platinum is commonly used since it is relatively free from corrosive effects and has a high melting point. Suppose at 20.0°C the resistance of a platinum resistance thermometer is 164.2 2. When placed in a particular solution, the resistance is 187.4 2. What is the temperature of this solution?