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Kamila [148]
3 years ago
11

A voltage of 21.0V across the terminals of a device produces a current of 3.00 mA through the device. What is the resistance of

the device?
Physics
1 answer:
densk [106]3 years ago
8 0

Answer: 7,000 ohms

Explanation:

From the equation of ohms law V= IR

V=21 volt

I = 3 MA = 3.0×10^-3 A

So by evaluating, we have.

V= IR

21= 3.0×10^-3 × R

Then R = 21/3.0×10^-3

R= 7,000 ohms//.

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Because the air in their wings helps them fly
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Sometimes a person cannot clearly see objects close up or far away. To correct this type of vision, bifocals are often used. The
Rudik [331]

Answer:

1)   P₁ = -2 D,   2) P₂ = 6 D

Explanation:

for this exercise in geometric optics let's use the equation of the constructor

          \frac{1}{f} = \frac{1}{p} + \frac{1}{q}

where f is the focal length, p and q are the distance to the object and the image, respectively

1) to see a distant object it must be at infinity (p = ∞)

          \frac{1}{f_1} = \frac{1}{q}

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2) for an object located at p = 25 cm

            \frac{1}{f_2} = \frac{1}{25} + \frac{1}{q}

We can that in the two expressions we have the distance to the image, this is the distance where it can be seen clearly in general for a normal person is q = 50 cm

we substitute in the equations

1) f₁ = -50 cm

2)  

        \frac{1}{f_2} = \frac{1}{25} + \frac{1}{50}

        \frac{1}{f_2} = 0.06

         f₂ = 16.67 cm

the expression for the power of the lenses is

          P = \frac{1}{f}

where the focal length is in meters

           

1)       P₁ = 1/0.50

        P₁ = -2 D

2)     P₂ = 1 /0.16667

        P₂ = 6 D

4 0
3 years ago
A mover brings a box up the stairs in 10 seconds. If he applied a force of 20 N over a distance 10 m on the box, calculate the p
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Answer:

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W = (20 N) (10 m)

W = 200 Joules

Power = work / time

P = 200 J / 10 s

P = 20 Watts

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An object moves along the x axis. The graph shows it’s position x as a function of time t. Find the average velocity of the obje
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Question is from B to C

Answer: (b) 1.5m/s

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t1=1s, t2=5s
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Time elapsed, ∆t=(5-1)s=4s

So average velocity v =∆x/∆t=6/4=1.5m/s
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Keisha is making a diagram of a simple machine in the body.
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Answer:

Sorry for being late. It is...

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