MYTUTOR SUBJECT ANSWERS

614 views

What does the double slit experiment tell us about light?

Imagine an opaque barrier (no light can get through) with two parallel slits in it, onto which we shine a coherent light source (light of only one wavelength and in phase - a laser, for example, can produce this). There is a screen behind the barrier and slits.

 

What will the pattern on the screen look like?

 

If light was made up of tiny particles, like spraying tiny pellets towards the slits, we would expect that the particles which went towards a slit would fly straight through and land on the screen, forming two bright lines on the screen - one behind each slit. The photoelectric effect tells us that light acts with a particle nature, so this is what we should expect.

 

However this is not what we see with light!

 

With light, the pattern that emerges on the screen is a series of bright and dark bands, alternating across the screen (not just two bright bands). This is known as an interference pattern. This pattern is exactly what we would see if we had passed a water wave through the slits - strips where the wave was high and strips where the water was still. This results from the interference of waves.

This demonstrates that light has a wavelike nature, which seems to be contrary to what the photoelectric effect demonstrated. 

 

So which one is wrong?

 

Neither!

 

Amazingly, light sometimes acts like a wave and sometimes like particles - sometimes we have to think of it like waves to explain what happens and sometimes we have to think of it as made of particles.

 

This unusual property is called the wave-particle duality of light.

Adam O. GCSE Maths tutor, GCSE Physics tutor, A Level Maths tutor, A ...

2 years ago

Answered by Adam, an A Level Physics tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

90 SUBJECT SPECIALISTS

£20 /hr

Noam T.

Degree: Mathematics with Mathematical Physics (Bachelors) - University College London University

Subjects offered:Physics, Maths

Physics
Maths

“About Myself: I am an undergraduate student at UCL studying Mathematics with Mathematical Physics. Hoping to go into research after my degree, I have a true passion for my subjects and my aim is to pass on that passion to students in ...”

£24 /hr

Elizabeth H.

Degree: Natural Science (Masters) - Durham University

Subjects offered:Physics, Maths+ 2 more

Physics
Maths
Further Mathematics
Chemistry

“Hi! I'm a Natural Sciences student at Durham University studying Physics and Chemistry. I love learning science and applying it to the real world as well as exam and homework questions, and would love to help you do the same!I tutore...”

Alex A. GCSE Maths tutor, A Level Maths tutor, 13 Plus  Maths tutor, ...
£20 /hr

Alex A.

Degree: Physics (Masters) - Manchester University

Subjects offered:Physics, Science+ 4 more

Physics
Science
Maths
Drama
Chemistry
-Personal Statements-

“Hi, I'm currently studying for a Masters Degree in Physics at the University of Manchester. I'm keen on all things Maths and Science related, as well as having interests ranging from Rock Climbing to Acting. I've always thought that a ...”

About the author

Adam O.

Currently unavailable:

Degree: Physics (Masters) - Oxford, St Hugh's College University

Subjects offered:Physics, Maths+ 1 more

Physics
Maths
Further Mathematics

“Top tutor from the renowned Russell university group, ready to help you improve your grades.”

You may also like...

Other A Level Physics questions

Describe and explain the first stages of the life cycle of a star before it reaches the main sequence.

A particle that moves uniformly in a circular path is accelerating yet moving at a constant speed. Explain this statement.

(ii) Describe and explain how the horizontal component of the water jet varies from point X to point Y. (2 marks)

Describe how the strong nuclear force between nucleons varies with seperation of the nucleons.

View A Level Physics tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok