/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 34 When a resistor with resistance ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

When a resistor with resistance \(R\) is connected to a 1.50-V flashlight battery, the resistor consumes 0.0625 W of electrical power. (Throughout, assume that each battery has negligible internal resistance.) (a) What power does the resistor consume if it is connected to a 12.6-V car battery? Assume that \(R\) remains constant when the power consumption changes. (b) The resistor is connected to a battery and consumes 5.00 W. What is the voltage of this battery?

Short Answer

Expert verified
(a) 4.41 W with the 12.6-V battery. (b) Voltage is 13.42 V when the resistor consumes 5.00 W.

Step by step solution

01

Understanding Power Formula

The power consumed by a resistor is given by the formula \[ P = \frac{V^2}{R} \]where \(P\) is power, \(V\) is voltage, and \(R\) is the resistance.
02

Determine Resistance using 1.50-V Battery

Given that with a 1.50-V battery, the resistor consumes 0.0625 W of power, we can use the formula for power:\[ 0.0625 = \frac{1.50^2}{R} \]Solving for \(R\),\[ R = \frac{1.50^2}{0.0625} = \frac{2.25}{0.0625} = 36 \ \Omega \]
03

Calculate Power with 12.6-V Battery

Now, knowing \(R = 36 \ \Omega\), calculate the power consumed with a 12.6-V battery.\[ P = \frac{12.6^2}{36} \]\[ P = \frac{158.76}{36} = 4.41 \ W \]
04

Solve for Voltage when Power is 5.00 W

Given the same \(R = 36 \ \Omega\) and a power consumption of 5.00 W, use the power formula:\[ 5.00 = \frac{V^2}{36} \]Solving for \(V^2\),\[ V^2 = 5.00 \times 36 = 180 \]Therefore,\[ V = \sqrt{180} = 13.42 \ V \]

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Resistance Calculation
Resistance is a fundamental concept in electrical circuits. It's a measure of how much a resistor resists the flow of electric current. In this exercise, we started with a given power consumption and a known voltage to determine the resistance of a resistor. Using the power formula:\[ P = \frac{V^2}{R} \]The resistance \( R \) can be calculated if you rearrange the formula to:\[ R = \frac{V^2}{P} \]By substituting the given values from the exercise, with the voltage \( V = 1.50 \, V \) and power \( P = 0.0625 \, W \), we found that the resistance \( R = 36 \, \Omega \). This means the resistor restricts the flow of current such that it maintains this power consumption at the given voltage. Whenever you are achieving a resistance calculation, ensure all the units are consistent and check for accuracy by substituting back into the original power formula.
Power Formula
The power formula is an essential tool in electrical engineering and physics. It helps us calculate the power consumed by a circuit component using its voltage and resistance. The formula used in the task is:\[ P = \frac{V^2}{R} \]Here, \( P \) denotes the power in watts (W), \( V \) is the voltage in volts (V), and \( R \) is the resistance in ohms (\( \Omega \)).Power: Reflects how fast energy is being used or consumed by the resistor. It's a direct outcome of both voltage and resistance. The higher the power, the more energy is consumed quickly.
  • Voltage (\( V \)): How much potential energy is provided to push current through the resistor.
  • Resistance (\( R \)): Determines how much the resistor will oppose this flow of current.
Understanding this formula allows you to predict how a circuit will behave as different voltages are applied. It is a crucial stepping stone for many electrical calculations.
Voltage Calculation
Voltage represents the potential difference across a resistor. In this problem, we needed to calculate voltage when the power and resistance are known. To find voltage, the formula derived from the power equation is:\[ V = \sqrt{P \times R} \]For instance, to find the voltage needed to drive a 5.00 W power consumption through a resistor of 36 \( \Omega \), we used:\[ V^2 = 5.00 \times 36 = 180 \]And solved for \( V \):\[ V = \sqrt{180} \approx 13.42 \, V \]This voltage calculation helps us understand the potential energy necessary for a given power consumption. It also shows the tight relationship between power, resistance, and voltage — changing one inevitably affects the others, a key consideration when designing and troubleshooting circuits.
Ohm's Law
Though Ohm's Law was not directly used in the steps, it's a core principle underlying the calculations for resistance, power, and voltage. It states the relationship between voltage (V), current (I), and resistance (R) in an electric circuit:\[ V = I \times R \]What Ohm's Law tells us is:
  • Voltage (V): The potential difference that pushes the current through a resistor.
  • Current (I): The flow of electric charge through the resistor affected by the voltage and resistance.
  • Resistance (R): Property of the resistor that limits current flow.
This foundational law helps explain how various components interact within an electrical system. It serves as the background for understanding why calculations like those done in the exercise can predict circuit behavior. Knowing Ohm's Law equips you with the ability to navigate complex circuits and solve for unknown quantities.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

An idealized voltmeter is connected across the terminals of a 15.0-V battery, and a 75.0-\(\Omega\) appliance is also connected across its terminals. If the voltmeter reads 11.9 V, (a) how much power is being dissipated by the appliance, and (b) what is the internal resistance of the battery?

A typical small flashlight contains two batteries, each having an emf of 1.5 V, connected in series with a bulb having resistance \(17 \Omega\). (a) If the internal resistance of the batteries is negligible, what power is delivered to the bulb? (b) If the batteries last for 5.0 h, what is the total energy delivered to the bulb? (c) The resistance of real batteries increases as they run down. If the initial internal resistance is negligible, what is the combined internal resistance of both batteries when the power to the bulb has decreased to half its initial value? (Assume that the resistance of the bulb is constant. Actually, it will change somewhat when the current through the filament changes, because this changes the temperature of the filament and hence the resistivity of the filament wire.)

A typical cost for electrical power is $0.120 per kilowatthour. (a) Some people leave their porch light on all the time. What is the yearly cost to keep a 75-W bulb burning day and night? (b) Suppose your refrigerator uses 400 W of power when it's running, and it runs 8 hours a day. What is the yearly cost of operating your refrigerator?

An external resistor with resistance \(R\) is connected to a battery that has emf \(\varepsilon\) and internal resistance \(r\). Let \(P\) be the electrical power output of the source. By conservation of energy, \(P\) is equal to the power consumed by \(R\). What is the value of \(P\) in the limit that \(R\) is (a) very small; (b) very large? (c) Show that the power output of the battery is a maximum when \(R = r\). What is this maximum \(P\) in terms of \(\varepsilon\) and \(r\)? (d) A battery has \(\varepsilon\) = 64.0 V and \(r =\) 4.00 \(\Omega\). What is the power output of this battery when it is connected to a resistor \(R\), for \(R =\) 2.00 \(\Omega\), \(R =\) 4.00 \(\Omega\), and \(R =\) 6.00 \(\Omega\) ? Are your results consistent with the general result that you derived in part (b)?

A resistor with resistance \(R\) is connected to a battery that has emf 12.0 V and internal resistance \(r =\) 0.40\(\Omega\). For what two values of \(R\) will the power dissipated in the resistor be 80.0 W?

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.