math

calculate the resistances of (a) 100-watt 120-volt incandescent lamp, (b) a 750-watt 115-volt toaster, (c) a 1300 watt 110-volt portable iron.

  1. 👍
  2. 👎
  3. 👁
  4. ℹ️
  5. 🚩
  1. A 72-ohm coil of wire is connected in series with an adjustable resistor (rheostat) whose resistance can be varied from 0 to 88 ohms. If the line potential is 115 volts, calculate (a) the range through which the coil current can be varied, (b) the rheostat resistance when the power taken by the coil is 90 watts

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
  2. a. 120I = 100 W.
    I = 0.833A

    R = V/I = 120/0.833 = 144 Ohms.

    b. Same procedure as a.

    c. Same procedure as a.

    a. Imax = V/(72+0) = 115/(72+0) = 1.60A
    Imin = 115/(72+88) = 0.719A

    b. P = V^2/(Rc+R) = 90 W.
    115^2/(72+R) = 90
    90*(72+R) = 115^2
    72+R = 146.94
    R = 146.94-72 = 74.94 Ohms=The rheostat
    resistance.

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩

Respond to this Question

First Name

Your Response

Similar Questions

  1. Electrotechnics N4

    A circuit,consisting of 3 resistances 12,18 & 36 ohms respectively joined in parallel is connected in series with fourth resistance.the whole is supplied at 60 volt & it is found that the power dissipated in the 12Ohm resistance

  2. science

    what resistance would produce a current of 120 amps from a 6-volt battery?

  3. chemistry

    A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 525 nm , how many photons are emitted per second?

  4. Science

    Electric bulb is Marked 60 watts 120 volt what is the resistance of filament of bulb

  1. Physics ASAP!!

    1. Three resistors are placed in series. They have the following resistances: R1 = 20 ohms, R2 = 20 ohms, R3 = 10 ohms. What current would be moved through this circuit by a 5-V power supply? A. 1.0 A B. 0.10 A C. 25 A D. 250 A 2.

  2. Algebra

    An amplifier has a 50 watt output and a 5 watt input. What is the gain in decibels for this amplifier, rounded to the nearest decibel?

  3. Physics

    Three resistors R₁, R₂, and R, are connected in series and to a 120-volt source. If R₂ = 2R₁, R3 = 3R₁, and the total power taken by the circuit is 200 watts, calculate (a) the resistance of each resistor, (b) the power

  4. Science

    What is the current in the 30-ohm heating coil of a coffee maker that operates on a 120-volt circuit? Would be 120/30?

  1. Physics

    A 100 W lamp is connected to 120 V, and its current is measured. A resistor is added to the lamp to reduce the current to half its original value. (a) What is the potential difference across the lamp? (b) How much resistance was

  2. physics

    an operating 100-watt lamp is connected to a 120-volt outlet. what is the total energy used by the lamp in 60. seconds

  3. Physics

    A 100-Watt light bulb plugged into a 120-Volt outlet is left on for 60 seconds. How much energy (in Joules) is used up by the bulb during this time?

  4. physics.

    please check my answers. when a lamp is plugged into a 120 V socket, each coulomb of charge that flows in the circuit is raised to a potential engergy of 120 joules? which offers more resistance to water flow, a wide pipe or

View more similar questions or ask a new question.