The Intensity of a light is multiplied with the Light color.

The value can be between 0 and 8. This allows you to create over bright lights.

	// Pulse light's intensity over time
	var duration : float= 1.0;
	function Update() {
		// argument for cosine
		var phi : float = Time.time / duration * 2 * Mathf.PI;
		// get cosine and transform from -1..1 to 0..1 range
		var amplitude : float = Mathf.Cos( phi ) * 0.5 + 0.5;
		// set light color
		light.intensity = amplitude;
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    public float duration = 1.0F;
    void Update() {
        float phi = Time.time / duration * 2 * Mathf.PI;
        float amplitude = Mathf.Cos(phi) * 0.5F + 0.5F;
        light.intensity = amplitude;
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	public duration as float = 1.0F

	def Update() as void:
		phi as float = (((Time.time / duration) * 2) * Mathf.PI)
		amplitude as float = ((Mathf.Cos(phi) * 0.5F) + 0.5F)
		light.intensity = amplitude