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
SVEN [57.7K]
3 years ago
8

At one point in the circuit, there is an LED and a resistor in parallel with one another. If you measure the voltage drop across

the LED as 2.1 V and the current through the LED as 20 mA, you know: Group of answer choices a) The current through the resistor is 20 mA b) The voltage drop across the resistor is 2.1 V and its current is 20 mA c) The voltage drop across the resistor is 2.1 V nothing about the current through or voltage drop across the resistor.
Physics
1 answer:
kifflom [539]3 years ago
7 0

Answer:

C. The voltage drop across the resistor is 2.1V and nothing about the current through the resistor.

Explanation:

When connected in parallel, voltage across the resistances are the same. So if 2.1V was dropped across the LED then 2.1V was also dropped across the resistor. However, this tells us nothing about the current through the resistor. We can find the current across the resistor if we know the resistance of the resistor, but that's about it.

If it were a series connection, then the current would have been the same, but the voltage drop were another story.

You might be interested in
A 500kg car is driven forward with a thrust force of 1500N. Air resistance and friction acts against the motion of the car with
Wittaler [7]
2m/s^2, this is because F=ma, meaning a is also equal to F/m. The car applies 1500N in one direction and outside sources apply a total of -500N, meaning the 500kg car is moving forward with a total of 1000N of force. Taking the total 1000N and dividing it by 500kg gives you and acceleration of 2m/s^2. Hope this helps!
8 0
2 years ago
In case A below, a 1 kg solid sphere is released from rest at point S. It rolls without slipping down the ramp shown, and is lau
mestny [16]

Answer:

the block reaches higher than the sphere

\frac{y_{sphere}} {y_block} = 5/7

Explanation:

We are going to solve this interesting problem

A) in this case a sphere rolls on the ramp, let's find the speed of the center of mass at the exit of the ramp

Let's use the concept of conservation of energy

starting point. At the top of the ramp

         Em₀ = U = m g y₁

final point. At the exit of the ramp

         Em_f = K + U = ½ m v² + ½ I w² + m g y₂

notice that we include the translational and rotational energy, we assume that the height of the exit ramp is y₂

energy is conserved

          Em₀ = Em_f

         m g y₁ = ½ m v² + ½ I w² + m g y₂

angular and linear velocity are related

        v = w r

the moment of inertia of a sphere is

         I = \frac{2}{5} m r²

we substitute

         m g (y₁ - y₂) = ½ m v² + ½ (\frac{2}{5} m r²) (\frac{v}{r})²

         m g h = ½ m v² (1 + \frac{2}{5})

where h is the difference in height between the two sides of the ramp

h = y₂ -y₁

         mg h = \frac{7}{5} (\frac{1}{2} m v²)

         v = √5/7  √2gh

This is the exit velocity of the vertical movement of the sphere

         v_sphere = 0.845 √2gh

B) is the same case, but for a box without friction

   starting point

          Em₀ = U = mg y₁

   final point

          Em_f = K + U = ½ m v² + m g y₂

          Em₀ = Em_f

          mg y₁ = ½ m v² + m g y₂

          m g (y₁ -y₂) = ½ m v²

          v = √2gh

this is the speed of the box

          v_box = √2gh

to know which body reaches higher in the air we can use the kinematic relations

          v² = v₀² - 2 g y

at the highest point v = 0

           y = vo₀²/ 2g

for the sphere

           y_sphere = 5/7 2gh / 2g

           y_esfera = 5/7 h

for the block

           y_block = 2gh / 2g

            y_block = h

       

therefore the block reaches higher than the sphere

         \frac{y_{sphere}} {y_bolck} = 5/7

3 0
3 years ago
The average coefficient of linear expansion of copper is 1.7 10-5 (°c)−1. the statue of liberty is 93 m tall on a summer morning
sammy [17]

Let the rise in temperature be 5^0C

The expansion in length due to change in temperature is given by the expression lαΔt , where l is the length, α is the  coefficient of linear expansion, Δt is the change in temperature.

Here l = 93 m, α = 1.7*10^{-5}  ^0C^{-1}, and Δt = 5^0C

So expansion in length = 93*1.7*10^{-5}*5 = 0.007905 m = 0.79*10^{-3}m

So order of magnitude in change in length = -3


3 0
3 years ago
Read 2 more answers
The fact that Mercury has no atmosphere is evidence that it _____.
Naddika [18.5K]
We want to know what does the fact that Mercury has no atmosphere tell us. Since Mercury has no atmosphere it cant reflect a lot of sunlight that is hitting its surface. Its constantly being hit by solar wind. So Mercury reflects a small percentage of the sunlight that strikes it. 
7 0
3 years ago
Read 2 more answers
Cual sera el caudal que lleva un rio cuando se desplaza a 200 litros cada 40 segundos
alisha [4.7K]

Answer:

Q = 5 L/s

Explanation:

To find the flow you use the following formula (para calcular el caudal usted utiliza la siguiente formula):

Q=\frac{V}{t}

V: Volume (volumen) = 200L

t: time (tiempo) = 40 s

you replace the values of the parameters to calculate Q (usted reemplaza los valores de los parámteros V y t para calcular el caudal):

Q=\frac{200L}{40s}=5\frac{L}{s}

Hence, the flow is 5 L/s (por lo tanto, el caudal es de 5L/s)

4 0
3 years ago
Other questions:
  • Air can be considered a mixture. Which statement does not help explain why?
    10·1 answer
  • A hydrogen atom is in its ground state when its orbital electron:
    7·1 answer
  • A wave has a wavelength of 8 mm and frequency of 3hertz.what is its speed?
    10·1 answer
  • You wish to place a spacecraft in a circular orbit around the earth so that its orbital speed will be 4.00×103m/s. What is this
    13·1 answer
  • A block of weight mg sits on an inclined plane as shown in (Figure 1) . A force of magnitude F1 is applied to pull the block up
    13·1 answer
  • Sand is made of tiny pieces of rock that have been worn
    7·2 answers
  • ou are pushing a 20-kg box along a horizontal floor. Friction acts on the box. When you apply a horizontal force of magnitude 48
    6·2 answers
  • Compare and contrast Continental Drift and Plate Tectonics.
    14·1 answer
  • Why does our sun appear larger than any other star in our galaxy
    7·2 answers
  • a physics student throws a stone horizontally off a cliff. one second later, he throws a second identical stone in exactly the s
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!