NECO June/July 2024 - Get offline past questions & answers - Download objective & theory, all in one app 48789
Join your school's WhatsApp group

2020 WAEC Physics Theory (a) (i) Define Optical angle. (ii) Explain two conditions necessary for total internal reflection to...

Physics
WAEC 2020

(a) (i) Define Optical angle.

(ii) Explain two conditions necessary for total internal reflection to occur. 

(iii) List three practical applications of total internal reflection.

(b) State two effects of refraction. 

(c)(i) Define progressive waves.

(ii) A plane progressive wave is represented by the equation y = 0.5 sin(1000\(\pi\)r = \(\frac{100 \pi \lambda}{17}\)) where y is in millimetres, t in seconds and x in metres.  Calculate the: (\(\alpha\)) frequency of the wave; (\(\beta\))of the wave; (\(\gamma\)) speed of the wave

NECO June/July 2024 - Get offline past questions & answers - Download objective & theory, all in one app 48789
Project Topics and Materials, Post-UTME past questions - Download now or upload yours to get paid
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
Explanation

(a) (i) The angle of incidence in the optically denser medium for which the angle of refraction in the less dense medium is 90\(^o\)

(ii) Conditions necessary for total internal reflection to occur:
- Light rays must travel from a dense medium to a less dense medium.

- Angle of incidence in the dense medium must be greater than the critical angle.

iii) Practical applications of total internal reflection

- Prism periscopes.

- Prism Binoculars.

- Fibre optics

- Fish eye view.

- Transmission of radio signals

 

(b) Effects of refraction

- straight objects placed in liquid appear bent (on the interface or boundary)

- mirages.

- dispersion of white light/formation of rainbow.

- apparent displacement of objects placed in liquids/apparent shadows of pools base.

(c)(i) Definition of progressive waves: A disturbance which travels through a medium that enables energy to be transferred from its source to another (without the particles of the medium transferred). OR Transfer of energy and momentum from the source of disturbances. 

 

(ii) (\(\alpha\)) calculation of frequency of wave

y = 0.5 sin (1000) \(\pi\) t - 100 \(\pi \frac{x}{17}\)

= a sin (2\(\pi ft - 2 \pi \frac{x}{\gamma}\))

= 2\(\pi f = 1000 \pi\)

f = 500Hz

(\(\beta\)) calculation of wavelength of wave

\(\frac{2\pi}{\lambda} = \frac{100\pi}{17}\)

\(\lambda\) = \(\frac{2 \times 17}{100}\)

= 0.34m

(\(\gamma\) calculation of speed of wave)

v = f\(\lambda\)

= 500 x 0.34

170ms\(^{-1}\)


Report an Error Ask A Question Download App
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
Project Topics and Materials, Post-UTME past questions - Download now or upload yours to get paid
Join your school's WhatsApp group

Contributions ({{ comment_count }})

Please wait...

{{ settings.no_comment_msg ? settings.no_comment_msg : 'There are no comments' }}

Quick Questions

Post your Contribution

Please don't post or ask to join a "Group" or "Whatsapp Group" as a comment. It will be deleted. To join or start a group, please click here

{{ quote.posted_by.display_name }}
{{ settings.form_textarea_description }}
 
Project Topics and Materials, Post-UTME past questions - Download now or upload yours to get paid
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
Join your school's WhatsApp group
NECO June/July 2024 - Get offline past questions & answers - Download objective & theory, all in one app 48789
Project Topics and Materials, Post-UTME past questions - Download now or upload yours to get paid
Join your school's WhatsApp group
Post-UTME Past Questions - Original materials are available here - Download PDF for your school of choice + 1 year SMS alerts
NECO June/July 2024 - Get offline past questions & answers - Download objective & theory, all in one app 48789