Wireless Sensor Networks (WSNs) operate with varying duty cycles to meet their application-specific criteria such as the availability, reliability, and the life expectancy of the system. This variation in duty cycle consequently affects the system characteristics including the interference and collision of signals. However, the sensitivity to physical jamming attacks with respect to duty cycle of the network is not widely explored area of research. This paper presents a detailed analysis of the effect of the duty cycle to the interference and collision of signals in the WSNs. In particular, our simulation model depicts a log normal shadowing model to represent a realistic wireless channel and observe the effects of duty cycle variation when a physical jamming attack is launched on the network using a compromised node. Our results show that setting the duty cycle at predetermined value would help minimize the packet drop ratio of the network.