PRELIMINARY STAGE 2026
Contest 13
St. Francis Xavier Jnr. Sem.: 56 points
Pentecost SHS: 25 points
Nana Brentu SHS: 13 points
Contest 14
Ofori Panin SHS: 53 points
Mim SHS: 42 points
Oyoko Methodist SHS: 36 points
ROUND 2 - SPEED RACE
QUESTION
Identify, if any, the wavelength(s) visible to the unaided human eye among these electromagnetic wavelengths: 55 nm, 550 nm, and 5500 nm.
ANSWER: 550 nm
SOLUTION:
Where:
$\lambda_{UV}$ = Ultraviolet/X-ray region wavelength (55 nm)
$\lambda_{Visible}$ = Visible spectrum peak green wavelength (550 nm)
$\lambda_{IR}$ = Deep infrared region wavelength (5500 nm)
Comparison:
$400 nm \le \lambda_{Visible} \le 700 nm$
$\lambda_{UV} < 400 nm$ (Invisible)
$\lambda_{IR} > 700 nm$ (Invisible)
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PRACTICE QUESTIONS
1. QUESTION: Identify, if any, the wavelength(s) visible to the unaided human eye among these electromagnetic wavelengths: 62 nm, 620 nm and 6200 nm.
ANSWER: 620 nm or $6.2\times10^{2}$ nm
SOLUTION:
Visible light runs from about 400 nm to about 700 nm.
62 nm is ultraviolet and 6200 nm is infrared.
2. QUESTION: Identify, if any, the wavelength(s) visible to the unaided human eye among these electromagnetic wavelengths: 45 nm, 450 nm and 4500 nm.
ANSWER: 450 nm or $4.5\times10^{2}$ nm
SOLUTION:
Only 450 nm lies between about 400 nm and 700 nm; it looks blue.
3. QUESTION: Identify, if any, the wavelength(s) visible to the unaided human eye among these electromagnetic wavelengths: 35 nm, 350 nm and 3500 nm.
ANSWER: None of them
SOLUTION:
350 nm is just below the visible range (ultraviolet); 35 nm is far ultraviolet and 3500 nm is infrared.
4. QUESTION: Identify, if any, the wavelength(s) visible to the unaided human eye among these electromagnetic wavelengths: 58 nm, 580 nm and 5800 nm.
ANSWER: 580 nm or $5.8\times10^{2}$ nm
SOLUTION:
580 nm lies in the visible range and looks yellow.
5. QUESTION: Identify, if any, the wavelength(s) visible to the unaided human eye among these electromagnetic wavelengths: 480 nm, 530 nm and 670 nm.
ANSWER: All three
SOLUTION:
All three lie between about 400 nm and 700 nm: blue, green and red.
6. QUESTION: Identify, if any, the wavelength(s) visible to the unaided human eye among these electromagnetic wavelengths: 85 nm, 850 nm and 8500 nm.
ANSWER: None of them
SOLUTION:
850 nm is near infrared, above the red limit of about 700 nm.
7. QUESTION: Which colour of visible light has the shortest wavelength?
ANSWER: Violet
SOLUTION:
Violet is at the short-wavelength end of the visible spectrum, near 400 nm.
8. QUESTION: Which colour of visible light has the longest wavelength?
ANSWER: Red
SOLUTION:
Red is at the long-wavelength end of the visible spectrum, near 700 nm.
9. QUESTION: Name the region of the electromagnetic spectrum just beyond red light.
ANSWER: Infrared
SOLUTION:
Infrared has longer wavelengths than red light.
10. QUESTION: Name the region of the electromagnetic spectrum just beyond violet light.
ANSWER: Ultraviolet
SOLUTION:
Ultraviolet has shorter wavelengths than violet light.
11. QUESTION: Which region of the electromagnetic spectrum has wavelengths of about one nanometre down to about one hundredth of a nanometre?
ANSWER: X-rays
SOLUTION:
X-rays lie between ultraviolet and gamma rays.
12. QUESTION: To which colour is the human eye most sensitive in bright light?
ANSWER: Green (near 555 nm)
SOLUTION:
The eye's daylight sensitivity peaks in the green-yellow region.