A laser produces 15.0mW of light. In 3.00hr , the laser emits 4.53×1020 photons. What is the wavelength of the laser?

I don't know what you're doing wrong with your calculator but you need to find out and get it under control.

162/4.53E20 = approx 40E-20 or 4E-19 (I think the actual number is 3.57E-19). (both numbers wrong). My final answer comes out to be about 5.6E-7 m which is about 560 nm.

1 watt = 1 J/s

15 watt = 15 J/s
15 milliwatts = 15 millijoules/s =0.015 J/s
0.015 J/s x (60 s/min) x (60 m/hr) x (3 hrs) = ? total Joules This E is for 4.53E20 photons so total J/4.53E20 = energy in J/1 photon. Then
E in J/photon = hc/wavelength. Solve for wavelength.

I got 5.56*10^-45 which doesn't make sense?

If you will show your work perhaps I can find it as in the other laser problem.

I think the error is in the exponent.

.015*60*60*3= 1.62*10^2 so 1.62*10^2/4.53*10^20= 7.34*10^22 so 7.34*10^22= (6.626*10^-34)(3.00*10^8)/wavelength and I solved for wavelength and got 2.71*10^-4 this tim

To find the wavelength of the laser, we can use the formula:

wavelength = c / frequency

where c is the speed of light and frequency is the number of cycles of the wave per second.

Since we are given the power of the laser (15.0mW) and the number of photons emitted in a given time (4.53×1020 photons in 3.00hr), we can use these values to find the frequency.

First, we need to convert the power of the laser from milliwatts to watts:
Power (in watts) = Power (in milliwatts) / 1000
Power = 15.0mW / 1000 = 0.015 W

Next, we need to convert the time from hours to seconds:
Time (in seconds) = Time (in hours) x 60 x 60
Time = 3.00hr x 60 x 60 = 10800s

Now, we can find the frequency using the formula:
frequency = Power / (Planck's constant x number of photons emitted)
Planck's constant = 6.626 x 10^-34 J*s (joule-seconds)

frequency = 0.015 W / (6.626 x 10^-34 J*s x 4.53×10^20 photons)
frequency ≈ 3.919 x 10^14 Hz

We can now substitute the values of the speed of light (c) and frequency into the wavelength formula:
wavelength = c / frequency
speed of light (c) = 3.00 x 10^8 m/s (meters per second)

wavelength = (3.00 x 10^8 m/s) / (3.919 x 10^14 Hz)
wavelength ≈ 7.66 x 10^-7 m

Therefore, the wavelength of the laser is approximately 7.66 x 10^-7 meters (or 766 nm).