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3 years ago

6

A lab technician needs to clean medical instruments that have been exposed to bacteria. Which electromagnetic wave would be most

useful for this task?

2 answers:

matrenka [14]3 years ago

6 0

Ultraviolet waves kill bacteria and germs.

Semenov [28]3 years ago

6 0

Answer: The correct answer is ultraviolet wave.

Explanation:

Electromagnetic wave is the wave in which both electric field and magnetic field are perpendicular to each other to the direction of the motion of the wave.

For example, Ultraviolet wave.

Ultraviolet wave is very harmful wave. The exposure of this wave can cause skin cancer.

This radiation has been used for disinfectant. Ultraviolet wave is used by a lab technician to clean medical instruments that have been exposed to bacteria. Bacteria contain DNA which is vulnerable to ultraviolet radiation. This radiation inactivates or kills the microbes.

Therefore, the correct answer is ultraviolet wave.

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(5) A 4 kg. object rests on a flat, horizontal surface with a static

baherus [9]

Answer:

F = 9.81 [N]

Explanation:

To solve this problem we must use Newton's third le which tells us that the sum of forces on a body that remains static must be equal to one resulting from these forces in the opposite direction.

Let's perform a summation of forces on the vertical axis-y to determine the normal force N.

∑F = 0 (axis-y)

$N - m*g = 0$

where:

m = mass = 4 [kg]

g = gravity acceleration = 9.81 [m/s²]

$N - (4*9.81)=0\\N = 39.24 [N]$

Now we know that the frictional force can be calculated using the following equation.

f = μ*N

where:

f = friction force [N]

μ = friction coefficient = 0.25

N = normal force = 39.24 [N]

Now replacing:

$f = 0.25*39.24\\f = 9.81[N]$

Then we perform a sum of forces on the X-axis equal to zero. This sum of forces allows us to determine the minimum force to be able to move the object in a horizontal direction.

∑F = 0 (axis-x)

$F-f=0\\F-9.81=0\\F= 9.81[N]$

If the coefficient was smaller, a smaller force (F) would be needed to start the movement, this can be easily seen by replacing the value of 0.25, by smaller values, such as 0.1 or 0.05.

If the coefficient were larger, a larger force would be needed.

3 0

3 years ago

Occupants in a single space shuttle in orbit feel weightless. describe a scheme whereby occupants in a pair of shuttles (or even

agasfer [191]

The scheme whereby occupants in a pair of shuttles is as follows
use a strong cable with large weight on the end
Then use the orbital naneuvering system(OMS) to set the whole work as spinning about their common center of gravity.

8 0

3 years ago

A student is experimenting with some insulated copper wire and a power supply. She winds a single layer of the wire on a tube wi

OverLord2011 [107]

Answer:

$P=214.7187\,W$

Explanation:

Given that:

Diameter of the solenoid, $D=10\,cm=0.1\,m$

length of the solenoid, $L=90\,cm=0.9\,m$

diameter of the wire, $d=0.1\,cm=10^{-3}\,m$

magnetic field at the center of the solenoid, $B=7.4\times 10^{-3}\,T$

<u>Now we need the no. of turns incorporated in the length of 90 cm:</u>

$N=\frac{Length\,\,of\,\,solenoid}{diameter\,\,of\,\, wire}$

$N=\frac{L}{d}$

$N=\frac{0.9}{10^{-3}}$

$N=900\,\,turns$

For solenoids we have:

$B=\mu.n.I$ ...............................(1)

where:

$\mu=$ permeability of the medium

n = no. of turns per unit length

I = current in the coil

So,

$n=\frac{900}{0.9}$

$n=1000\,turns\,.\,m^{-1}$

Now putting the respective values in the eq. (1)

$7.4\times 10^{-3}=4\pi\times10^{-7}\times 1000\times I$

$I=5.8887\,A$

For copper we have resistivity:

$\rho=1.72\times 10^{-8}\, \Omega.m$

We know that resistance is given by:

$R=\rho.\frac{l}{a}$ .....................................(2)

where:

l = length of the conducting wire

a = cross sectional area of the conducting wire

<u>Now we need the length (l) of the wire:</u>

Circumference of the solenoid,

$C=\pi.D$

$C=0.1\pi\,m$

$\therefore l=C\times N$

$l=90\pi\,m$

&

<u>Cross-sectional area of wire:</u>

$a=\pi.\frac{d^2}{4}$

$a=\pi. \frac{(10^{-3})^2}{4}\,m^2$

<u>Resistance from eq. (2):</u>

$R=1.72\times 10^{-8}\times \frac{90\pi}{\pi. \frac{(10^{-3})^2}{4}}$

$R=6.192 \,\Omega$

For power we have:

$P=I^2.R$

$P=5.8887^2 \times 6.192$

$P=214.7187\,W$

6 0

3 years ago

Determine the resistance of a 250-w lightbulb connected to its proper source voltage of 110 v.

ollegr [7]

1.P=UI
2.U=IR
so P=U^2/R
R=U^2/P=110*110/250=48.4ohm

5 0

3 years ago

How do u calculate momentum

Helga [31]

Answer:

Explanation:

To calculate the momentum of a moving object multiply the mass of the object times its velocity. The symbol for momentum is a small p. So, the momentum of the object is calculated to be 8.0 kg-m/s. Note the unit for momentum.

5 0

4 years ago