1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
snow_tiger [21]
3 years ago
7

You have 2 resistors of unknown values you label Ra and Rb. You have an old battery and a multimeter you bought years ago for 7$

at Harbor Freight. Using the meter in voltage mode, you measure 10 V across the battery. You then connect the 2 resistors in series across the battery and use the meter in current mode to find the current flowing through the circuit. It reads 0.111A. You then connect the 2 resistors in parallel across the battery and use the meter again to measure the current now coming from the battery to be 0.5A. With this information you have gathered, you find the value of the 2 resistors.
Value of smallest resistance in ohms.
a. 60
b. 90
c. 20
d. 30
Physics
1 answer:
Veseljchak [2.6K]3 years ago
6 0

Answer:

the answers, the correct one is D,   Rb₂ = 29.97 ohm

Explanation:

For this exercise we use ohm's law and the equivalent resistance ratio for series and parallel circuits.

Serial circuit

         (Ra + Rb) is = V

         (Ra + Rb) 0.111 = 10

         (Ra + Rb) = 10 / 0.111 = 90.09

parallel circuit

         \frac{1}{R} = \frac{1}{Ra} + \frac{1}{Rb}

           R = \frac{Ra \ Rb}{Ra + Rb}

          \frac{Ra \ Rb}{Ra + Rb} i_p = V

         \frac{Ra \ Rb}{Ra + Rb} 0.5 = 10

         \frac{Ra \ Rb}{Ra + Rb} = 10 / 0.5 = 20

we write and solve our system of equations

         Ra + Rb = 90.09

         \frac{Ra \ Rb}{Ra + Rb} = 20

         

we solve for Ra in the first equation

          Ra = 90.09 - Rb

           RaRb = 20 (Ra + Rb)

we substitute Ra in the second equation

           (90.09-Rb) Rb = 20 [(90.09-Rb) + Rb]

            90.09 Rb - Rb² = 20 90.09

           

            Rb² - 90.09 Rb + 1801.8 = 0

we solve the quadratic equation

            Rb = [90.09 ±\sqrt{90.09^2 - 4 \ 1801.8} ] / 2

            Rb = [90.09 ± 30.15] / 2

            Rb₁ = 60.12 ohm

            Rb₂ = 29.97 ohm

the smallest value is Rb = 30 ohm

When checking the answers, the correct one is D

You might be interested in
A wave is produced from a vibrating string on a violin. Two observers are standing 20 m and 40 m away from the musician. The obs
max2010maxim [7]

Well the one that is closer can see and hear more

3 0
3 years ago
Imagine Two Artificial Satellites Orbiting Earth At The Same Distance. One Satellite Has A Greater Mass Than The Other One? Whic
Bad White [126]

After reading this whole question, I feel like I've already
earned 5 points !

-- Two satellites at the same distance, different masses:

The forces of gravity between two objects are directly
proportional to the product of the objects' masses.  In
other words, the gravitational forces between the Earth
and an object on its surface are proportional to the mass of
the object.  In other words, people with more mass weigh more
on the Earth, and the Earth weighs more on them. 

If the satellites are both at the same distance from Earth,
then the Earth pulls on the one with more mass with greater
force, and also the one with more mass pulls on the Earth
with greater force.

-- Two satellites with the same mass, at different distances:

The forces of gravity between two objects are inversely
proportional to the square of the distance between them. 
In other words, the gravitational forces between the Earth
and an object are inversely proportional to the square of
the distance between the object and the center of the Earth. 

If the satellites both have the same mass, then the Earth
pulls on the nearer one with greater force, and also the
nearer one pulls on the Earth with greater force.

-- Resistor in a circuit when the voltage changes:

The resistance depends on how the resistor was manufactured. 
Its resistance is marked on it, and doesn't change.  It remains
the same whether the voltage changes, the current changes,
the time of day changes, the cost of oil changes, etc.

If you increase the voltage in the circuit where that resistor is
installed, the current through the resistor increases.  If the current
remains constant, then you can be sure that somebody snuck over
to your circuit when you weren't looking, and they either installed
another resistor in series with the original one to make the total
resistance bigger, or else they snipped the original one out of the
circuit and quickly connected one with more resistance in its place.

6 0
3 years ago
The velocity of a body is given by the equation v= a + bx, where 'x' is displacement. The unit of b is .......
valina [46]

Answer:

s^ -1    ( or    1/sec)

Explanation:

Velocity is given in units of displacement / sec

like feet /sec   or   m/sec    

so b would have units of   s^-1

(or perhaps a more general term would be   time^-1)

8 0
2 years ago
What is the name for the compound with a chemical formula B 6 Si?
USPshnik [31]
The answer is c C is the correct answer
8 0
3 years ago
Read 2 more answers
a particle moves in an elliptical or circular motion. it is most likely a particle in which type of wave
Strike441 [17]
Surface waves from an earthquake shake the ground back and forth and up and down. So basically in a circular motion. This wave is the most dangerous wave released during and earthquake and it comes after the p and s waves. The Surface wave is the last wave that comes after the other 2. So yea' these surface waves move in a circular motion.
5 0
3 years ago
Other questions:
  • Which of the following happens during a lunar eclipse? The moon appears red. The moon casts a shadow on Earth. Earth, the moon a
    9·2 answers
  • If your speedometer has an uncertainty of 2.5 km/h at a speed of 92 km/h, what is the percent uncertainty
    7·1 answer
  • A lightbulb has a resistance of 195 Ω and carries a current of 0.62 A.
    15·1 answer
  • Considering this analogy (current = rate that heat flows through a window, and voltage = temperature difference across the windo
    8·2 answers
  • A skiy diver, with parachute unopened, falls 625 m in 15.0s.
    13·1 answer
  • What is a lunar eclipse?
    14·2 answers
  • A 4 kg object moving to the left collides with and sticks to a 3 kg object moving to the right. Which of the following is true o
    11·1 answer
  • What is the main incentive for using a traditional economy? A. profit B. stability C. progress D. economic equality Please selec
    12·2 answers
  • so i had to work for halloween, my first Halloween working. When i got home my lil bro showed me all the candy he collected so i
    11·2 answers
  • Which of the following units would need to be converted before being used for a calculation
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!