Constants Part A For the circuit shown in the figure (Figure 1) both meters are idealized, the battery has no appreciable internal resistance, and the ammeter reads 1.70 A. What does the voltmeter read? ΜΕ ΑΣΦ V-541.14 Submit Previous Answers Request Answer * Incorrect; Try Again; 5 attempts remaining Figure www 45.0 Ω 25.0 Ω www 15.0 Ω www 15.0 Ω + 35.0 Ω ε= ? 1 of 1 Part B What is the emf of the battery? E = 541 V Submit Previous Answers 10.0 Ω Correct Provide Feedback ? V Next

The power dissipated in a resistor is given by P = V2/R, which means power decreases if resistance increases. Yet this power is also given by P = I2R, which means power increases if resistance increases. Explain why there is no contradiction here.

Currents of approximately 0.06 A can be potentially fatal. Currents in that range can make the heart fibrillate (beat in an uncontrolled manner). The resistance of a dry human body can be approximately 100 k . (a) What voltage can cause 0.06 A through a dry human body? (b) When a human body is wet, the resistance can fall to 100 . What voltage can cause harm to a wet body?

For the circuit shown in Figure P28.55. the ideal voltmeter reads 6.00 V and the ideal ammeter reads 3.00-k. Find (a) the value of K, (b) the emf of the battery, and (c) the voltage across the 3.00-kft resistor.

A 50resistor is connected across the emf v(t)=(160V)sin(120t) . Write an expression for the current throug1 the resistor.

Consider the circuit in Figure 21.29 and assume the batter has no internal resistance. (i) Just after the switch is closed, what is the current in the battery? (a) 0 (b) /2R (c) 2/R (d) /R (e) impossible to determine (ii) After a very long time, what is the current in the battery? Choose from the same choices.

A person with body resistance between his hands of 1.00 k accidentally grasps the terminals of a 20.0-kV power supply. (Do NOT do this!) (a) Draw a circuit diagram to represent the situation. (b) If the internal resistance of the power supply is 2000 , what is the current through his body? (c) What is the power dissipated in his body? (d) If the power supply is to be made safe by increasing its internal resistance, what should the internal resistance be for the maximum current in this situation to be 1.00 mA or less? (e) Will this modification compromise the effectiveness of the power supply for driving low-re si stance devices? Explain your reasoning,

An automobile starter motor has an equivalent resistance of 0.0500 and is supplied by a 12.0-V battery with a 0.0100- internal resistance, (a) What is the current to the motor? (b) What voltage is applied to it? (c) What power is supplied to the motor? (d) Repeat these calculations for when the battery connections are corroded and add 0.0900 to the circuit. (Significant problems are caused by even small amounts of unwanted resistance in low-voltage, high-current applications.)

Three identical 60.0-W, 120-V lightbulbs are connected across a 120-V power source as shown in Figure P28.72. Assuming the resistance of each lightbulb is constant (even though in reality the resistance might increase markedly with current), find (a) the total power supplied by the power source and (b) the potential difference across each lightbulb.

How does the resistance for copper and for silicon change with temperature? Why are the behaviors of these two materials different?