Question

Eye is most sensitive to
A. \[20\,{A^0}\] LIGHT
B. \[1000{A^{^0}}\]LIGHT
C. \[5000{A^{^0}}\]LIGHT
D. \[7000{A^{^0}}\]LIGHT

Answer 1

Hint: The retina of the human eye is made up of photoreceptor cells. These photoreceptor cells are rods and cones. Rods are responsible for vision in low light or night vision and cones are responsible for vision in daylight. This photoreceptor cell contains a chemical which responds to light.

Complete answer: Photoreceptor cell layer is followed by nervous layer. This nervous layer consists of bipolar neurons along with amacrine cells, ganglion neuron and horizontal cells. The functions of these cells are to conduct nerve impulses from photoreceptor cells and transfer them to the optic nerve. The nervous layer is followed by the optic-nerve. This nerve carries nerve impulses from the eye to the occipital lobe of the brain. In this occipital lobe, decoding of visual information takes place. So, the pathway of nerve impulse is from photoreceptor cells to the nervous layer to optic nerve, while the pathway of light is quite opposite i.e. from the nervous layer to the photoreceptor cells layer. Due to the fall of light on photoreceptor cells, i.e. the protein present inside the cones gets changed. These proteins are opsin and retinal. In absence of light, opsin is in Cis-form and are attached with the retina, when light falls on cones, the cis form of opsin gets changed to trans-opsin. Due to this, the detachment of opsin from the retina takes place and leads to the generation of a nerve impulse. When light does not fall on cones, the opsin again gets back to cis-form and gets attached with the retina. This conformational change in opsin leads to the generation of an action potential and due to this change, the person can visualize objects.The human eye is sensitive to a wavelength of \[5000{A^{^0}}\]LIGHT.
So, the correct answer is option C.

Note: The wavelength of \[5000{A^{^0}}\] corresponds to greenlight of the visible spectrum. Humans produce the highest brightness to green colour. The point where optic nerve leaves the eye is called the blind spot because here, photoreceptor cells i.e. rods and cones are absent and when light rays fall on the blind spot, the person is unable to visualize objects.