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3 years ago

why can light from the sun cause skin cancer but the light from a light bulb cannot cause skin cancer?

Physics

2 answers:

nordsb [41]3 years ago

8 0

Goopoood jooooobbbbbbbbb

meriva3 years ago

4 0

Answer:

Damage from UV exposure is cumulative and increases your skin cancer risk over time. While your body can repair some of the DNA damage in skin cells, it can't repair all of it. The unrepaired damage builds up over time and triggers mutations that cause skin cells to multiply rapidly. That can lead to malignant tumors.

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An isolated conducting sphere has a 17 cm radius. One wire carries a current of 1.0000020 A into it. Another wire carries a curr

notsponge [240]

14 ms is required to reach the potential of 1500 V.

Explanation:

The current is measured as the amount of charge traveling per unit time. So the charge of electrons required for each current is determined as the product of current with time.

$Charge = Current \times Time$

As two different current is passing at two different times, the net charge will be the different in current. So,

$\text { Charge }=(1.0000020-1.0000000) \times t=2 \times 10^{-6} \times t$

The electric voltage on the surface of cylinder can be obtained as the ratio of charge to the radius of the cylinder.

$V=\frac{k q}{R}$

Here $k = 9 * 10^9$ , q is the charge and R is the radius. As $q=2 \times 10^{-6} \times t$ and R =17 cm = 0.17 m, then the voltage will be

$V=\frac{9 \times 10^{9} \times 2 \times 10^{-6} \times t}{0.17}$

The time is required to find to reach the voltage of 1500 V, so

$1500 =\frac{9 \times 10^{9} \times 2 \times 10^{-6} \times t}{0.17}$

$\begin{aligned}&t=\frac{1500 \times 0.17}{\left(9 \times 10^{9} \times 2 \times 10^{-6}\right)}\\&t=14.1666 \times 10^{-3} s=14\ \mathrm{ms}\end{aligned}$

So, 14 ms is required to reach the potential of 1500 V.

3 0

3 years ago

A magnet is moved in and out of a coil of wire connected to a high-resistance voltmeter. If the number of coils doubles, the ind

Varvara68 [4.7K]

Answer:

A. Doubles.

Explanation:

In an electromagnetic device such as a generator, when a wire (conductor) moves through the magnetic field between the South and North poles of a magnet, an electromotive force (e.m.f) is usually induced across a wire

The mode of operation of a generator is that a metal core with copper tightly wound to it (conductor coil) rotates rapidly between the two (2) poles of a horseshoe magnet type. Thus when the conductor coil rotates rapidly, it cuts the magnetic field existing between the poles of the horseshoe magnet and then induces the flow of current.

When a high-resistance voltmeter is connected to an electric circuit, a deflection will arise due to the flow of electricity. Moving the magnet towards the coil of wire will cause the needle of the high-resistance voltmeter to move in one direction. Also, as the magnet is moved out from the coil of wire, the needle of the high-resistance voltmeter moves in the opposite direction.

In this scenario, a magnet is moved in and out of a coil of wire connected to a high-resistance voltmeter. If the number of coils doubles, the induced voltage doubles because the number of turns (voltage) in the primary winding is directly proportional to the number of turns (voltage) in the secondary winding.

4 0

3 years ago

The angular momentum of an electron in each of its orbits must be some multiple of:

Nastasia [14]

The Bohr's proposal for the angular momentum of an electron in Bohr's model of the hydrogen atom is:

L=(n*h)/(2π), where n is the number of the energy level and h is the Planck's constant. This equation shows us the quantization of angular momentum of the electron. So the correct answer is the second one: Planck's constant.

7 0

3 years ago

If a planet's orbital speed is 20 km/s when it's at its average distance from the sun which is most likely orbital speed when it

Alona [7]

Answer:25km/s

Explanation:

8 0

3 years ago

A girl drops a stone from the top a tower 45m tall. At the same time, a boy standing at the base of the tower, projects another

Advocard [28]

Answer:

(i) The stones meet at 1.8 second

(ii) The point at which the stones meet, is 28.8 m above the base of the building and 16.2 m below the top of the building.

Explanation:

(i)

First we consider the stone dropped by the girl. We have data:

Vi = Initial Velocity of Stone = 0 m/s (Since the stone was initially at rest)

t = Time Period

g = 10 m/s²

s₁ = Distance Covered by Stone

Using 2nd equation of motion, we get:

s₁ = Vi t + (0.5)gt²

s₁ = (0)(t) + (0.5)(10)t²

s₁ = 5t² ----- equation (1)

Now, we consider the stone throne vertically upward by the boy. We have data:

Vi = Initial Velocity of Stone = 25 m/s

t = Time Period

g = - 10 m/s² (negative sign due to upward motion)

s₂ = Distance Covered by Stone

Using 2nd equation of motion, we get:

s₂ = Vi t + (0.5)gt²

s₂ = (25)(t) + (0.5)(-10)t²

s₂ = 25t - 5t² ----- equation (2)

At, the point where both the stones meet, the sum of distances covered by both stones must be equal to the height of building (i.e 45 m).

s₁ + s₂ = 45

using values from equation (1) and equation (2)

5t² + 25t - 5t² = 45

25t = 45

t = 45/25

t = 1.8 sec

(ii)

using this value of of t in equation (2)

s₂ = (25)(1.8) - (5)(1.8)²

s₂ = 28.8 m

using this value of of t in equation (1)

s₁ = (5)(1.8)²

s₁ = 16.2 m

Hence, the point at which the stones meet, is 28.8 m above the base of the building and 16.2 m below the top of the building.

6 0

3 years ago