Calculating Resistance of Resistor for 12V/10W Lamp & 24V Accumulator

  • Thread starter Thread starter chawki
  • Start date Start date
  • Tags Tags
    Lamp Resistor
Click For Summary

Homework Help Overview

The discussion revolves around calculating the resistance needed for a resistor in series with a 12V/10W lamp connected to a 24V power source. The subject area includes electrical circuits and Ohm's law.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants explore the relationship between voltage, current, and resistance in a series circuit. Questions are raised about the necessary voltage across the lamp and how to calculate the required resistance for the series resistor.

Discussion Status

Some participants have provided calculations and reasoning regarding the voltage requirements and current flow in the circuit. There is an ongoing exploration of the values derived and whether they are accurate, with requests for validation of the calculations presented.

Contextual Notes

Participants are working under the constraints of the problem statement, which specifies the lamp's voltage and power ratings, as well as the total voltage of the power source. There is an implicit assumption about the series circuit configuration and the need for additional resistance.

chawki
Messages
504
Reaction score
0

Homework Statement


A lamp is marked 12V/10W. the lamp is connected to 24V accumulator. in series with lamp you must then connect a resistor.
Calculate the resistance of the resistor.


Homework Equations





The Attempt at a Solution

 
Physics news on Phys.org
What quantity is the same throughout a series circuit?
Can you calculate the value of this quantity that the bulb requires?
 
to lamp to work properly 12V and current I (which is according to P=IV) has to be provided. So apart from this 12V the rest of the 12V of the supply has to be given to the resistor in series.Now you know the voltage across the resistor and the current (which is same I). Now it's simple:)
 
P=V2/RL
RL=V2/P = 122/10
RL= 14.4 Ohms.
we know that when connecting in series, I=IL=IR
and also V=VL+VR

VL = RL * IL
IL = 12/14.4 = 0.83Amps.
so, V=Req * I
Req = V/I
RL+RR = V/I
RR = V/I - RL
= (24/0.83) - 14.4
= 14.5 Ohms.

PLEASE TELL ME IF IT'S TRUE.
 

Similar threads

A circuit involving two non-linear resistances (incandescent lamps)
  • · Replies 14 ·
Replies
14
Views
2K
An interesting GCSE question: Why are electric lamps connected in parallel in house wiring?
  • · Replies 14 ·
Replies
14
Views
906
Draw circuit, % increase in the resistance
  • · Replies 13 ·
Replies
13
Views
2K
Current Flow Through Lamps in Circuits
  • · Replies 9 ·
Replies
9
Views
2K
Understanding the Voltage Across a Broken Lamp
  • · Replies 4 ·
Replies
4
Views
2K
Why a lamp with X PD passes Y current
  • · Replies 23 ·
Replies
23
Views
3K
Why Does a Lamp Light Up Slowly When Connected with a NTC Thermistor?
  • · Replies 7 ·
Replies
7
Views
4K
Circuits question, series vs parallel
  • · Replies 5 ·
Replies
5
Views
2K
Question about changing resistance and power
  • · Replies 1 ·
Replies
1
Views
2K
Understanding the Effects of Shorted Lamp A on Power Supply
  • · Replies 4 ·
Replies
4
Views
2K