Gr 9 NATURAL SCIENCES: CH 3.3 Uses of resistors

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Questions and Answers

What is the effect of increasing the resistance in a circuit?

  • The voltage increases
  • The current decreases (correct)
  • The energy transfer becomes more efficient
  • The current increases

What is the purpose of a rheostat in a circuit?

  • To adjust the current in a circuit (correct)
  • To decrease the current in a circuit
  • To increase the voltage in a circuit
  • To convert electrical energy into light

What type of energy is wasted in a system?

  • Output energy
  • Input energy
  • Energy lost to the surroundings (correct)
  • Useful energy

What is the function of a resistor in protecting an LED?

<p>To decrease the current flow through the LED (B)</p> Signup and view all the answers

What is represented by the symbol?

<p>A rheostat (D)</p> Signup and view all the answers

What happens to the brightness of a light bulb when the resistance of a rheostat is decreased?

<p>It becomes brighter (B)</p> Signup and view all the answers

What is the direction of current flow through an LED?

<p>In one direction (D)</p> Signup and view all the answers

What is the primary function of a diode?

<p>To allow current to flow in one direction (A)</p> Signup and view all the answers

What is the main advantage of LEDs over incandescent bulbs?

<p>They are more efficient (B)</p> Signup and view all the answers

According to the Sankey diagram, what percentage of input energy is wasted as heat in an incandescent bulb?

<p>90% (D)</p> Signup and view all the answers

What is the percentage of useful output energy from an LED according to the Sankey diagram?

<p>80% (B)</p> Signup and view all the answers

What is the primary difference between an incandescent bulb and an LED?

<p>The efficiency of energy conversion (A)</p> Signup and view all the answers

What is the purpose of a Sankey diagram?

<p>To compare the efficiency of different lighting systems (C)</p> Signup and view all the answers

Why do LEDs convert a higher percentage of electrical energy into light?

<p>Because they are designed to minimize energy waste (C)</p> Signup and view all the answers

What is the main benefit of replacing incandescent bulbs with LEDs?

<p>They reduce energy waste (A)</p> Signup and view all the answers

What is the main purpose of using a resistor in a circuit with an LED?

<p>To control the current flow and protect the LED (C)</p> Signup and view all the answers

What is the result of increasing the resistance in a circuit with a fixed voltage?

<p>The current decreases (A)</p> Signup and view all the answers

What is the main function of a rheostat in a circuit?

<p>To control the current flow in a circuit (C)</p> Signup and view all the answers

What happens to the energy that is not converted into useful output energy in a system?

<p>It is wasted as heat energy or other forms (D)</p> Signup and view all the answers

What is the primary advantage of using a rheostat in a circuit with a motor?

<p>To control the speed of the motor (A)</p> Signup and view all the answers

What is the main difference between the energy transferred in a system and the energy wasted in a system?

<p>Useful energy and wasted energy (C)</p> Signup and view all the answers

What is the primary function of a resistor in an electrical circuit?

<p>To control the current flow in a circuit (B)</p> Signup and view all the answers

What is the primary role of a diode in a circuit?

<p>To direct current flow (C)</p> Signup and view all the answers

Why are LEDs becoming a popular choice for lighting?

<p>They are more energy-efficient (A)</p> Signup and view all the answers

What do the Sankey diagrams illustrate?

<p>Energy transfer in different systems (C)</p> Signup and view all the answers

What is a key difference between the energy output of incandescent bulbs and LEDs?

<p>LEDs produce less waste energy (D)</p> Signup and view all the answers

What is a benefit of using LEDs in households?

<p>They reduce energy waste (C)</p> Signup and view all the answers

What is the main advantage of using a diode in a circuit?

<p>It directs current flow in one direction (A)</p> Signup and view all the answers

What does the Sankey diagram show about the incandescent bulb?

<p>It produces 10% useful light (D)</p> Signup and view all the answers

What is a characteristic of LEDs in terms of energy conversion?

<p>They convert most energy into light (B)</p> Signup and view all the answers

What is the effect of increasing the resistance in a circuit with a fixed voltage, according to Ohm's Law?

<p>The current decreases (B)</p> Signup and view all the answers

What is the primary function of a rheostat in devices such as sound equipment?

<p>To control the current in a circuit (B)</p> Signup and view all the answers

What is the primary reason why a resistor is used to protect an LED in a circuit?

<p>To prevent the LED from burning out due to high current (B)</p> Signup and view all the answers

What is the primary difference between energy transfers in systems and energy waste in systems?

<p>Energy transfers are useful, while energy waste is not (D)</p> Signup and view all the answers

What is the primary advantage of using a rheostat in a circuit with a motor?

<p>It allows for the control of the motor's speed (D)</p> Signup and view all the answers

What is the primary function of a resistor in an electrical circuit?

<p>To regulate the current in a circuit (D)</p> Signup and view all the answers

What is the primary reason why a diode is used in a circuit?

<p>To control the direction of current flow (B)</p> Signup and view all the answers

What is the primary benefit of using LEDs in households?

<p>They convert a higher percentage of electrical energy into light (D)</p> Signup and view all the answers

What is the main difference between the efficiency of incandescent bulbs and LEDs?

<p>Incandescent bulbs produce more heat, while LEDs produce more light (A)</p> Signup and view all the answers

What is the primary benefit of using a Sankey diagram?

<p>To illustrate the efficiency of an energy system (B)</p> Signup and view all the answers

What is the main characteristic of a diode that makes it useful in electronic devices?

<p>Low resistance to current flow in one direction and high resistance in the other direction (A)</p> Signup and view all the answers

What is the primary advantage of replacing incandescent bulbs with LEDs in households?

<p>LEDs convert a higher percentage of electrical energy into light (B)</p> Signup and view all the answers

What is the purpose of comparing the efficiency of incandescent bulbs and LEDs?

<p>To illustrate the difference in energy conversion between the two (C)</p> Signup and view all the answers

What is the main reason why LEDs are becoming a popular choice for lighting?

<p>They are more efficient and waste less energy as heat (C)</p> Signup and view all the answers

What is the primary difference between the Sankey diagrams for incandescent bulbs and LEDs?

<p>The wasted energy is different (D)</p> Signup and view all the answers

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