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3 years ago

Nearsightedness can be corrected by using eyeglass lenses that are

2 answers:

8 0

Nearsightedness can be corrected by using eyeglass lenses that are D. concave in shape and cause light rays entering the eyes to diverge.

Mamont248 [21]3 years ago

6 0

Answer:

Concave in shape and cause light rays entering the eyes to diverge.

Explanation:

Nearsightedness is also called myopia. It is a defect in the human eye in which a person is able to see nearby objects clearly but the far objects are seen blurry. In this type of defect, the light is unable to focus on the retina as a result far objects appears blurry.

For the correction of this defect a concave lens is used. It helps to cause light entering eyes to diverge. So, the correct option is (d).

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If a 60-g object has a volume of 30 cm", what is its density?

alisha [4.7K]

Answer:

Density = Mass/volume. D= 60/30.Divide it and you'll get ur answer as 2

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3 years ago

An experiment is set up to test the angular resolution of an optical device when red light (wavelength ????r ) shines on an aper

Neko [114]

Explanation:

As per Rayleigh criterion, the angular resolution is given as follows:

$\theta=\frac{1.22 \lambda}{D}$

From this expression larger the size of aperture, smaller will be the value of angular resolution and hence, better will be the device i.e. precision for distinguishing two points at very high angular difference is higher.

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4 years ago

A heater has a resistance of 10.0 Ω. It operates on a 12.0 V. What is the current through the resistor?

irakobra [83]

Answer:

1.2 amps :)

Explanation:

A heater has a resistance of 10.0 Ω. It operates on a 12.0 V. What is the current through the resistor?

Known:

R = 10.0 Ω

V = 12.0 V

Unknown:

I = ???

I = V/R

= 12.0 V / 10.0 Ω

= 1.2 amps

6 0

3 years ago

A common physics demonstration is to drop a small magnet down a long, vertical aluminum pipe. Describe the motion of the magnet

Rzqust [24]

Answer and Explanation:

This experiment is known as Lenz's tube.

The Lenz tube is an experiment that shows how you can brake a magnetic dipole that goes down a tube that conducts electric current. The magnet, when falling, along with its magnetic field, will generate variations in the magnetic field flux within the tube. These variations create an emf induced according to Faraday's Law:

$\varepsilon =-\frac{d\phi_B}{dt}$

This emf induced on the surface of the tube generates a current within it according to Ohm's Law:

$V=IR$

This emf and current oppose the flux change, therefore a field will be produced in such a direction that the magnet is repelled from below and is attracted from above. The magnitude of the flux at the bottom of the magnet increases from the point of view of the tube, and at the top it decreases. Therefore, two "magnets" are generated under and above the dipole, which repel it below and attract above. Finally, the dipole feels a force in the opposite direction to the direction of fall, therefore it falls with less speed.

7 0

3 years ago

Read 2 more answers

A cat dozes on a stationary merry-go-round, at a radius of 5.5 m from the center of the ride. Then the operator turns on the rid

bixtya [17]

Answer:

$u_{s}=0.56$

Explanation:

For the cat to stay in place on the merry go round without sliding the magnitude of maximum static friction must be equal to magnitude of centripetal force

$F_{s.max}=\frac{mv^2}{r} \\$

Where the r is the radius of merry-go-round and v is the tangential speed

but

$F_{s.max}=u_{s}F_{N}=u_{s}mg$

So we have

$u_{s}mg=\frac{mv^2}{r}\\ u_{s}=\frac{v^2}{gr}\\ Where\\v=\frac{2\pi R}{T} \\So\\u_{s}=\frac{(\frac{2\pi R}{T} )^2}{gr} \\u_{s}=\frac{4\pi^2 r}{gT^2}$

Substitute the given values

$u_{s}=\frac{4\pi^2 5.5m}{(9.8m/s^2)(6.3s)^2} \\u_{s}=0.56$

6 0

3 years ago