A circuit you’re building needs an ammeter that goes from 0 mA to a full-scale reading of 50 mA. Unfortunately, the only ammeter in the storeroom goes from
a. What value of R must you use so that the meter will go to full scale when the current I is 50 mA?
b. What is the effective resistance of your ammeter?
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PHYS 212 FOR SCI+ENG W/MAST PHYS >ICP<
- A lightbulb is connected to a variable power supply. As the potential across the bulb is varied, the resulting current and the filaments temperature are measured. The data are listed in Table P28.38. a. Find R for each entry in Table P28.38, and then plot R as a function of T. b. Assume that room temperature is at 293 K. Find R0 (resistance at room temperature). Comment on your result.arrow_forwardFigure P29.45 shows five resistors connected between terminals a and b. a. What is the equivalent resistance of this combination of resistors? b. What is the current through each resistor if a 24.0-V battery is connected across the terminals?arrow_forwardWhat is the equivalent resistance between points a and b of the six resistors shown in Figure P29.70? FIGURE P29.70arrow_forward
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- Four resistors are connected to a battery as shown in Figure P21.40. The current in the battery is I, the battery emf is , and the resistor values are R1 = R, R2 = 2R, R3 = 4R, and R4 = 3R. (a) Rank the resistors according to the potential difference across them, from largest to smallest. Note any cases of equal potential differences. (b) Determine the potential difference across each resistor in terms of . (c) Rank the resistors according to the current in them, from largest to smallest. Note any cases of equal currents. (d) Determine the current in each resistor in terms of I. (e) If R3 is increased, what happens to the current in each of the resistors? (f) In the limit that R3 , what are the new values of the current in each resistor in terms of I, the original current in the battery? Figure P21.40arrow_forwardIn the circuit of Figure P27.20, the current I1 = 3.00 A and the values of for the ideal battery and R are unknown. What are the currents (a) I2 and (b) I3? (c) Can you find the values of and R? If so, find their values. If not, explain. Figure P27.20arrow_forwardA battery is used to charge a capacitor through a resistor as shown. Show that half the energy supplied by the battery appears as internal energy in the resistor and half is stored in the capacitor.arrow_forward
- The brightness of a lightbulb is dependent on the current that goes through the lightbulb (in reality on the power, which is I^2/R). In Europe, the voltage used is 220 Volts, as opposed to the 120 Volts used in the USA. Will a lighbulb that is made for European voltage work well or poorly in the USA? It will work poorly in the USA. Since I=V/R, if V decreases, so does I, and so does the brightness. It will work more efficiently in the USA. Since I=V/R, if V decreases, I increases, and the brightness increases. It will work better in the USA because the resistance of the wires is smaller. Whether it works better or worse depends on how modern the wiring system is, regardless of the voltage, V.arrow_forwardFigure P28.15 2) Using Kirchhoffs rules, (a) find the current in each resistor in Figure (28.24). (b) Find the potential difference between points c and f. Which point is at the higher potential? 4.00 k2 E2 R3 E3 60.0 V 80.0 V 70.0 V I2 13 I1 R2 3.00 k2 2.00 k2 a R1 Figure 28.24:arrow_forwardIn the circuit shown in Figure OQ28.12, each battery is delivering energy to the circuit by electrical transmission. All the resistors have equal resistance. (i) Rank the electric potentials at points a, b. c, d, and e from highest to lowest, noting any cases of equality in the ranking. (ii) Rank the magnitudes of the currents at the same points from greatest to least, noting any cases of equality.arrow_forward
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